D&D General Lore Questions About Spelljamming Uses of Magic, Cosmology, Metaphysics

[caerus]

I know that 5e has left most of this stuff out so far, and I know that a lot of this has probably been deliberately left out of most or all editions because its pointlessly analytic and rarely adds to the game. But I also know I'm not the only nerd who has asked these questions, so there must be at least hints where there aren't answers. I'm trying to put together the most sensible take that favors the most modern written lore whenever possible, but fills in the gaps with the next most recent thing, RAI. I've seen a lot of "its not supposed to be answered" around the internet. I'm not interested in that at all. I'm looking for the best universal theory on the dnd multiverse in 5e, that will definitely depend on older books.

5e great wheel

------

Here are the quick, bottom lines that I have gathered so far about spelljamming, magic use, and the dnd universe. Please help me in my goal by correcting anything here or filling anything else in for it to be more comprehensive:


-Each rough solar system is contained in a crystal sphere, which is some kind of incredible barrier that even prevents gods from using their magic on other worlds. For example, Greyhawk had moons as a source of magic, FR has more traditional gods.


-Gods don't seem to be able to exist on multiple worlds unless they have other worshipers there.


-Magic in 5e is accessed through the weave, thanks to "the essence of Mystra".


-----


cosmology


Can you could travel from, say, FR to Greyhawk? Do the different campaign settings exist on the same material plane, or does each setting essentially have its own material plane? Is it all broad enough to contain a place for real-world Earth? Is there a sci-fi place without magic at all, where magic is impossible? Are there infinite places?


magic

If gods have any control over magic, why not just cut it off in certain places to further their goals?


What is "the weave"? PHB says "the essence of Mystra", and that "all magic depends on the Weave". I hear that its an interface mortal use to access magic, but why do you need spell components to do that, and how does a spellcasting focus alleviate that need? Why are some items consumed when casting the spell? What happens to them?


If you can travel between campaign settings, wouldn't a (divine) caster lose their magic when they leave their home crystal sphere, but maybe not a wizard? If the weave is everywhere, seems that wizards access it through study, while divine casters need their gods to assist.


How does a God like Mystra, or others create effects on the material plane? Do Gods need the Weave too? How did the Weave get created if there was no magic without it? If the Weave is just an interface, where is the origin of magic?


Do Psionics use the Weave? Do spelljamming races like Illithids or Gith make use of it everywhere?


Is "innate spellcasting" significant in lore or just a rule shorthand?


Metaphysics


I've seen references to Gods existing in multiple crystal spheres or campaign settings, so long as they have believers in each one. Why would that make a difference? If belief empowers/creates gods wouldn't a false god be impossible?


Where do gods exist? They have homes on out planes without regular rules of time/space, but it also seems that physical locations are important since they are in some way confined to crystal spheres in material space. How does that work?


What is a demiplane? Is it inside a certain crystal sphere?

 

[Leatherhead]

....
Can you could travel from, say, FR to Greyhawk?

Yes.

Do the different campaign settings exist on the same material plane, or does each setting essentially have its own material plane?

Depends on which lore you go with. At first every world was it's own Prime. Later all the Crystal Spheres were located in a single Prime.

Is it all broad enough to contain a place for real-world Earth?

Earth (or more exactly a game-based carbon copy of Earth) exists. Elminster himself has traveled there many times.

Is there a sci-fi place without magic at all, where magic is impossible? Are there infinite places?

It is implied that every single campaign setting and homebrew setting exists somewhere out there.

If gods have any control over magic, why not just cut it off in certain places to further their goals?

Specifically in FR (the default D&D world for 5e) there is someone called Ao who prevents the gods from going too crazy. Outside of FR, there are other such binding forces. Though gods, and people who have godlike powers, have been known to shut magic down before. It did not end well for most of them.

What is "the weave"? PHB says "the essence of Mystra", and that "all magic depends on the Weave". I hear that its an interface mortal use to access magic, but why do you need spell components to do that, and how does a spellcasting focus alleviate that need? Why are some items consumed when casting the spell? What happens to them?

The Weave is implied to be Mystra's Metaphysical body. The Weave is not necessary for magic to exist, it just makes magic more accessible. Spell components are largely a literal joke (bat guano and sulfur make gunpowder), the spellcasting focus is a metagame construct that gives people permission to be less silly with magic.

If you can travel between campaign settings, wouldn't a (divine) caster lose their magic when they leave their home crystal sphere, but maybe not a wizard? If the weave is everywhere, seems that wizards access it through study, while divine casters need their gods to assist.

Divine casters might find their magical prowess diminished depending on how far away they are from their god (and specifically being in the home of an enemy god). But otherwise every spell they can cast works perfectly. A Wizard (and other arcane casters) might find that the spells they are familiar with simply don't work properly on a different plane. There are items that allow either to bypass these limitations. These restrictions were mostly removed in 3e.

How does a God like Mystra, or others create effects on the material plane? Do Gods need the Weave too? How did the Weave get created if there was no magic without it? If the Weave is just an interface, where is the origin of magic?

Gods don't need the Weave to use magic. Gods use their divine power, which is determined by the number of their worshipers. Raw Magic (that is to say magic without the weave) is basically the physics of the world, it has existed as long as "stuff" has existed, and long before the Weave or even gods existed. The Weave is one part User Interface and one part safety net that prevents creation from being overpowered by Raw Magic. The Weave itself has fallen, three times. Once when Karsus (the Lord of the magical empire of Netheril) tried to become the new god of magic, and Mystryl (the goddess of magic before Mystra) had to sacrifice herself in order to fix everything. The Second time happened in the Time of Troubles, when the gods were Banished to the planet, and Mystra was killed (though later resurrected). And a third time during the Spellpague (caused by two planets merging) when Mystra was killed yet agan (she also came back from this one). Basically every time the Edition changes Mystra Dies.

Do Psionics use the Weave? Do spelljamming races like Illithids or Gith make use of it everywhere?

Yes and No. Psionics are a sore spot. Sometimes they are explicitly not magic and don't interact with the weave at all. Other times they are simply magic via an alternate means.

Is "innate spellcasting" significant in lore or just a rule shorthand?

it's significant in that it's considered to be a natural part of a creatures biology. Some creatures, like dragons, don't have to use the weave to cast spells.

I've seen references to Gods existing in multiple crystal spheres or campaign settings, so long as they have believers in each one. Why would that make a difference? If belief empowers/creates gods wouldn't a false god be impossible?

Beings can have a divine spark without having worshipers. Also gods tend to be very protective of their "terf", and don't want interlopers eating into their worshiper pools.

Where do gods exist? They have homes on out planes without regular rules of time/space, but it also seems that physical locations are important since they are in some way confined to crystal spheres in material space. How does that work?

Gods are metaphysical beings. I can't really give a better explanation than that.

What is a demiplane? Is it inside a certain crystal sphere?

Demiplanes are extremely small planes that exist somewhere outside of the Prime. Which would place them outside of a crystal sphere.

 

[Bohandas]

Spell components are largely a literal joke (bat guano and sulfur make gunpowder)

It's not a joke, it's sympathetic magic

 

[Urriak Uruk]

cosmology

Can you could travel from, say, FR to Greyhawk? Do the different campaign settings exist on the same material plane, or does each setting essentially have its own material plane? Is it all broad enough to contain a place for real-world Earth? Is there a sci-fi place without magic at all, where magic is impossible? Are there infinite places?

Yes, you can! FR and Greyhawk exist together on the "Material Plane," as do most D&D worlds like Athas, Krynn, and Exandria. To travel from FR to Greyhawk without the use of plane shifting magic, one can use a Spelljammer (which is like a ship that can go through space) to leave your planet, and then in turn leave your world's Crystal Sphere. From there, you go through the Astral Plane to the Crystal Sphere of the world of Greyhawk.

There is only one Material Plane, and most setting exist within it. Real-world Earth exists on the Material Plane. All homebrew worlds exist within the Material Plane, unless you have created your own cosmology. For that reason, the Material Plane is almost infinite. There are so many worlds created at D&D tables, each one different (even different versions of say FR), that to count them all would be a pointless exercise, and the Material Plane is continually growing in scope as people create their own worlds. However, it is not actually infinite.

magic

If gods have any control over magic, why not just cut it off in certain places to further their goals?

What is "the weave"? PHB says "the essence of Mystra", and that "all magic depends on the Weave". I hear that its an interface mortal use to access magic, but why do you need spell components to do that, and how does a spellcasting focus alleviate that need? Why are some items consumed when casting the spell? What happens to them?

If you can travel between campaign settings, wouldn't a (divine) caster lose their magic when they leave their home crystal sphere, but maybe not a wizard? If the weave is everywhere, seems that wizards access it through study, while divine casters need their gods to assist.

How does a God like Mystra, or others create effects on the material plane? Do Gods need the Weave too? How did the Weave get created if there was no magic without it? If the Weave is just an interface, where is the origin of magic?

Do Psionics use the Weave? Do spelljamming races like Illithids or Gith make use of it everywhere?

Is "innate spellcasting" significant in lore or just a rule shorthand?

Gods control over magic depends on the world; sometimes magic is not in their control at all. Sometimes it is, and they do control its usage to further their goals.

The "weave" is the magic network that spellcasters tap into when casting magic. The weave however is only really present in FR; other worlds have different systems for how magic works.

Certain spells require different components and steps to work, much like how a baker needs ingredients and an oven to bake. Sometimes replacing ingredients with replacements creates a similar result, like a focus. These resources are sometimes consumed, like sugar for making cookies, other times they are not, like a cookie cutter.

Sometimes, divine casters, and even wizards, do lose their magic when traveling to another world. A cleric who worships Bahamut may travel to the world of Athas, where there are no gods, and no longer be able to call forth his magic. A wizard from FR may also travel to Athas and lose his power, as Athas does not use the weave for magic but instead a process called "defiling," which the wizard may not know how to use (though he may learn it through more training).

There is no definitive answer to what the origin of magic is, and it is different on every world. Some worlds have no magic at all, others like FR have magic that is created by a god like Mystra, and others simply state that magic simply came into being on its own.

Psionics is not magic, but instead using the power of your mind to create effects that are often similar to magic. Illithids and Gith are both psionic races, and use this power very frequently instead of typical magic.

Innate spellcasting is a term used to describe beings/creatures that are innately magical, and are capable of using certain magic without having to use components. A dragon or giant for example, can use some spells without following the rules of a typical wizard of the same level.

Metaphysics

I've seen references to Gods existing in multiple crystal spheres or campaign settings, so long as they have believers in each one. Why would that make a difference? If belief empowers/creates gods wouldn't a false god be impossible?

Where do gods exist? They have homes on out planes without regular rules of time/space, but it also seems that physical locations are important since they are in some way confined to crystal spheres in material space. How does that work?

What is a demiplane? Is it inside a certain crystal sphere?

It is true that typically belief empowers and creates gods. This is not always the case; sometimes gods are powerful because they simply are, and have very few worshipers. But false gods may absolutely exist; if a concept simply does not have enough worshipers, it will not become a god. Sometimes, people worship gods that were killed long ago, and do not answer prayers; if that god gets enough worshipers, it is sometimes resurrected, but other times it is not.

Gods typically do not live on the Material Plane, though some have been known to take physical form and travel among the world they are worshiped on. Typically, a god forms their home in one of the outer planes, or in their own demiplane, and look upon the Material Plane from their home.

Demiplanes are smaller planes created by gods or even mortals, and can be as small as a large room. Although they can get very large, demiplanes cannot be infinite, unlike some of the Outer Planes (the Abyss for example has no known end). Demiplanes do not exist on the Material Plane, but are located within the Astral Plane.

 

[Enrico Poli1]

I know that 5e has left most of this stuff out so far, and I know that a lot of this has probably been deliberately left out of most or all editions because its pointlessly analytic and rarely adds to the game. But I also know I'm not the only nerd who has asked these questions, so there must be at least hints where there aren't answers. I'm trying to put together the most sensible take that favors the most modern written lore whenever possible, but fills in the gaps with the next most recent thing, RAI. I've seen a lot of "its not supposed to be answered" around the internet. I'm not interested in that at all. I'm looking for the best universal theory on the dnd multiverse in 5e, that will definitely depend on older books.

5e great wheel

------

Here are the quick, bottom lines that I have gathered so far about spelljamming, magic use, and the dnd universe. Please help me in my goal by correcting anything here or filling anything else in for it to be more comprehensive:


-Each rough solar system is contained in a crystal sphere, which is some kind of incredible barrier that even prevents gods from using their magic on other worlds. For example, Greyhawk had moons as a source of magic, FR has more traditional gods.


-Gods don't seem to be able to exist on multiple worlds unless they have other worshipers there.


-Magic in 5e is accessed through the weave, thanks to "the essence of Mystra".


-----


cosmology


Can you could travel from, say, FR to Greyhawk? Do the different campaign settings exist on the same material plane, or does each setting essentially have its own material plane? Is it all broad enough to contain a place for real-world Earth? Is there a sci-fi place without magic at all, where magic is impossible? Are there infinite places?


magic

If gods have any control over magic, why not just cut it off in certain places to further their goals?


What is "the weave"? PHB says "the essence of Mystra", and that "all magic depends on the Weave". I hear that its an interface mortal use to access magic, but why do you need spell components to do that, and how does a spellcasting focus alleviate that need? Why are some items consumed when casting the spell? What happens to them?


If you can travel between campaign settings, wouldn't a (divine) caster lose their magic when they leave their home crystal sphere, but maybe not a wizard? If the weave is everywhere, seems that wizards access it through study, while divine casters need their gods to assist.


How does a God like Mystra, or others create effects on the material plane? Do Gods need the Weave too? How did the Weave get created if there was no magic without it? If the Weave is just an interface, where is the origin of magic?


Do Psionics use the Weave? Do spelljamming races like Illithids or Gith make use of it everywhere?


Is "innate spellcasting" significant in lore or just a rule shorthand?


Metaphysics


I've seen references to Gods existing in multiple crystal spheres or campaign settings, so long as they have believers in each one. Why would that make a difference? If belief empowers/creates gods wouldn't a false god be impossible?


Where do gods exist? They have homes on out planes without regular rules of time/space, but it also seems that physical locations are important since they are in some way confined to crystal spheres in material space. How does that work?


What is a demiplane? Is it inside a certain crystal sphere?

COSMOLOGY
- Yes you can travel from FR to Greyhawk. With Spelljammer: FR, Greyhawk etc. are in different Crystal spheres in the same Prime Material Plane. There are infinite wolds in the infinite Prime Material Plane.
But there are also infinite Alternate Material Planes that you can visit via Planescape, that is planar travel. For example, you can visit real Earth or one of the infinite Alternate versions of Earth.
And yes, There are sci-fiction worlds without magic. The Multiverse is infinite enough to contain any thing you can think of.

PSIONICS
They are not magic and don't use the fabric of magic (in AD&D 2e)

METAPHYSICS

• Yes in D&D a "god" receives power from the belief of mortals. But there was much ambiguity on this topic in the history of the game. We could accept the idea that the gods, which inhabit their Realms in the Outer Planes, are only active in a world in which they have a large enough number of followers. Example: when people worshipping Tyr entered portals taking them to the FR, then Tyr could begin to be active in the Realms.
• Is it possible a false god? Yes, because a mortal could fake his divinity before the strenght of belief of millions faithful could really produce his divine ascension.
• Demiplanes are minor Planes, that can be as little a a single room. They are often created by mages that want a personal space; the creator can impose the physical rules of the Plane (ex.no air, no gravity, no passage of time, no magic). In AD&D 2e, they were contained in the Ethereal Plane.

 

[Bohandas]

For example, Greyhawk had moons as a source of magic, FR has more traditional gods.

Actually it was Dragonlance (Krynn) where the moons were the source of magic

Can you could travel from, say, FR to Greyhawk? Do the different campaign settings exist on the same material plane, or does each setting essentially have its own material plane?

Yes (unless a setting has incompatible assumptions about the outer planes, or, to a lesser extent, about the gods. ie. OG 3e Eberron (although I understand that in 5e the distantness of Eberron's gods was retconned to work like in Dark Sun...I think?)) although a special spell is needed to breach the crystal sphere and get out of one setting's star system or into another's

If gods have any control over magic, why not just cut it off in certain places to further their goals?

Attempts have been made in this regard. Takhisis (Tiamat) stole the planet Krynn out of its original crystal sphere in order to cut off the influence of the planet's other gods, and Tharizdun (The Elder Elemental Eye) tried to drain all the magical energy of Greyspace. In the end, Krynn's gods located the planet some decades later, and Tharizdun managed to piss off Greyspace's otherwise mellow primary god of magic Boccob (Baccab, Al-Zarad) who banded together with the other gods to banish Tharizdun from the multiverse

What is "the weave"? PHB says "the essence of Mystra", and that "all magic depends on the Weave".

Within the context of planescape/spelljammer that's more specifically "all magic within Mystra's sphere of influence depends on the weave"

why do you need spell components to do that

Look up "sympathetic magic" (and also, to a lesser extent, "law of contagion") on wikipedia

If you can travel between campaign settings, wouldn't a (divine) caster lose their magic when they leave their home crystal sphere, but maybe not a wizard? If the weave is everywhere, seems that wizards access it through study, while divine casters need their gods to assist.

Divine casters do indeed lose access in spheres where their deity does not hold sway (although I'm not sure offhand if it is lost totally or just partially). They also lose access in outer planes with alignments opposed to their deity's alignment (unless said plane is the main base of their deity's pantheon). The loss of power in alternate crystal spheres is mitigated if their deity's portfolio includes space travel or if their deity's influence is so widespread that their lack on influence in a particular crystal sphere is a fluke. The problems on opposed planes can be mitigated with a device called a "power key". I don't know if a power key works for foreign crystal spheres

Wizards have fewer problems, but many crystal spheres have their own idiosyncracies on that end too, such as Realmspace's weave, for example. Additionally, arcane magic has idiosyncracies on all outer planes, and to normalize it a seperate "spell key" is required for each school of magic

How does a God like Mystra, or others create effects on the material plane? Do Gods need the Weave too? How did the Weave get created if there was no magic without it? If the Weave is just an interface, where is the origin of magic?


Do Psionics use the Weave? Do spelljamming races like Illithids or Gith make use of it everywhere?

The weave is not all magic but merely magic as it functions in areas controlled by Mystra (generally Realmspace but theoretically also in any other place where she holds exclusive sway over magic. I don't recall the setting saying there are any other crystal spheres where she holds such sway, but I also don't recall it saying that there are not any)

In any case, she wouldn't control psionics unless psionics-magic transparency is in effect. That rule is explicitly optional.

As for the origin of magic, that's ambiguous, although both Vecna (the Flannish god of black magic) and Sharlee the Enchantress (the leader of a massive interplanar wizards' guild known as the Order of the Book) claim that it originates from an overdeity that they describe simply as "the serpent"

I've seen references to Gods existing in multiple crystal spheres or campaign settings, so long as they have believers in each one. Why would that make a difference? If belief empowers/creates gods wouldn't a false god be impossible?

The impression I've gotten is that it requires a certain critical mass of belief. Its not like Order of the Stick where one guy with some strange ideas about a sockpuppet he made can get said puppet almost accepted into the Norse pantheon. In most official material it usually seems like even organizations like the Believers in the Source, who specialize in manipulating belief to produce real effects, generally need some time and manpower if they want to screw around with the gods

Where do gods exist? They have homes on out planes without regular rules of time/space, but it also seems that physical locations are important since they are in some way confined to crystal spheres in material space. How does that work?

Usually their primary dwelling is on an outer plane that either A.) matches their alignment and/or B.) is the primary dwelling place of their entire pantheon.

They can remotely exercise power on worlds where they have a foothold from there.

Some gods have additional bases of operation in material worlds where they have influence. Krynn's gods of magic, for example, have holdings on the moons that bear their names.

An exception to the rule of dwelling on outer planes is that many demigods, especially those who only have influence on a single world, will often dwell on the material plane. The Greyhawk demigod Iuz, for example, directly rules a theocracy on Oreth.

What is a demiplane? Is it inside a certain crystal sphere?

They're seperate planes of existence (so not in a crystal sphere as those are part of the material plane). However, unlike normal planes they have finite size.

Although finite, the larger demiplanes can nonetheless be extremely large. There are several entire nations on the Demiplane of Dread (a plane which is also known by the toponym Ravenloft, after the capital of its most influential nation)

Traditionally most of them are accessed via the ethereal plane, although this is not a hard and fast rule.

In some of the earlier editions the Plane of Shadows/Shadowlie was a demiplane, although by 3e it had been retconned into a full plane.

Thougn they are not in a specific crystal sphere their limited size and scope means that there are fewer portals to a given demiplane than to a given normal plane and it would not be surprising for all permanent portals to a given demiplane to be in a single cryatal sphere or even a single building (IIRC the ONLY permanent portal to the Island Of The Ape is in Zagyg's castle)

 

[Aelryinth]

I know that 5e has left most of this stuff out so far, and I know that a lot of this has probably been deliberately left out of most or all editions because its pointlessly analytic and rarely adds to the game. But I also know I'm not the only nerd who has asked these questions, so there must be at least hints where there aren't answers. I'm trying to put together the most sensible take that favors the most modern written lore whenever possible, but fills in the gaps with the next most recent thing, RAI. I've seen a lot of "its not supposed to be answered" around the internet. I'm not interested in that at all. I'm looking for the best universal theory on the dnd multiverse in 5e, that will definitely depend on older books.

5e great wheel

------

Here are the quick, bottom lines that I have gathered so far about spelljamming, magic use, and the dnd universe. Please help me in my goal by correcting anything here or filling anything else in for it to be more comprehensive:


-Each rough solar system is contained in a crystal sphere, which is some kind of incredible barrier that even prevents gods from using their magic on other worlds. For example, Greyhawk had moons as a source of magic, FR has more traditional gods.

Greyhawk has general magic, it's overdeity of magic is Boccob. You are thinking of the Dragonlance world of Krynn. FR has a mostly singular pantheon, unlike Greyhawk, which has 3 active competing ones (more like Earth)

-Gods don't seem to be able to exist on multiple worlds unless they have other worshipers there.

That is correct, but they must have SUFFICIENT numbers to do so, if they are an existing god. This is considered expanding their inflence, and is generally regarded the same way you'd see a hobo setting up a tent on your front lawn.
False gods based on worship do exist in the setting.

-Magic in 5e is accessed through the weave, thanks to "the essence of Mystra".

Only in the Forgotten Realms, although using the term elsewhere doesn't hurt. The Weave, however, implies a Weaver, who is Mystra. In other worlds, magic might not need her control. The main reason behind the Weave is that both mortals and gods abuse the hell out of magic, and without the Weave there, it would all explode or collapse under their power-hungry fingers.

-----

cosmology


Can you could travel from, say, FR to Greyhawk? Do the different campaign settings exist on the same material plane, or does each setting essentially have its own material plane? Is it all broad enough to contain a place for real-world Earth? Is there a sci-fi place without magic at all, where magic is impossible? Are there infinite places?

Spelljammer is a way to travel from campaign world to world without leaving the Prime Material Plane. Leave the crystal sphere of your homeworld, go out into the phlogiston, sail to the new crystal sphere.
You can also do so by traveling through the Ethereal Plane, going into the deep ethereal and risking getting lost and nasty encounters; by finding the appropriate color pool in the Astral Plane (also daring encounters of soul-hunting outsiders and githyanki); or by plane-shifting to another plane, and then plane-shifting to the new world on the prime, if allowed to do so.
Technically speaking, a Wish or Interplanetary Teleport could get you to a new world, too.
Technically all game worlds are on the Prime Material Plane, but may be alternate dimensions within it, especially with house rules.
Earth exists and has been visited by both FR and Greyhawk natives in the past. There is a famous Dragon Magazine module where you go collect the Mace of St. Cuthbert, a divine artifact, from a museum on Earth. There's even elven jewelry on display there.
There are sci-fi settings with no magic at all, that have been visited by magic-users, and magic works there. Metamorphosis Alpha and the Starship Warden are classic tropes of this. So is Boot Hill, and characters often adventured from one to the other.
Where magic doesn't work at all? That is largely a DM call. There's no rule saying that characters with magic powers lose them in Star Frontiers or Star Trek. If you rule it so, then that's that. Can they DEVELOP them there? Without the classes, no.
Most planes are considered infinite, yet with borders, which is metaphysics at work. Paizo's Pathfinder world is set up like the real universe, without crystal spheres, for example. So, most planes you go on are infinite, but if you know how to, you can find the metaphysical border fairly easily.

magic

If gods have any control over magic, why not just cut it off in certain places to further their goals?

Because the other gods would turn it back on to further theirs. Generally, removing magic destroys worship of the divine, because they can't answer prayers. Gods can get ornery if you try to do that to them. Balance!

What is "the weave"? PHB says "the essence of Mystra", and that "all magic depends on the Weave". I hear that its an interface mortal use to access magic, but why do you need spell components to do that, and how does a spellcasting focus alleviate that need? Why are some items consumed when casting the spell? What happens to them?

It's a maintenance system for the magic of the realms.
FR is FULL of high level magic users. Seriously. Pretty much every major city has an archmage. Gods walked the lands, ancient dragons were everywhere, the elves had veritiable legions of archcasters, Netheril had post-30 casters, etc. They put massive amounts of pressure on magic, and the Weave was designed to keep the whole thing in place and working, without exploding and Bad Things Happening (like creating the Sea of Fallen Stars, and the Netheril Desert. Oops!)
Just think of it as another word for 'magic maintenance program', and Mystra sitting up there as the system overseer, and you're fine. Mechanically, it defines the limits on magic and how spells work, which is why magic is different between editions as the Weave gets a new operating system.

If you can travel between campaign settings, wouldn't a (divine) caster lose their magic when they leave their home crystal sphere, but maybe not a wizard? If the weave is everywhere, seems that wizards access it through study, while divine casters need their gods to assist.

YES!
This was actually one of the things addressed in Spelljammer. You actually could buy altars that would allow you to connect to your deity in foreign spheres.
It also encouraged you to be a pantheist, or a planarist. If you were a pantheist, any plane that worshipped a god in your pantheon, you had spells. So, someone worshipping the Norse, Finnish, and Greek Pantheons could get spells in Realmspace via Tyr, Mieklikki, and Sune (Venus) respectively (and the Egyptian, Chinese, Japanese, Indian, and Babylonian Pantheons are there, too). A planarist of the Seven Heavens could get their spells as long as any LG god living in the Seven Heavens was worshipped there.

How does a God like Mystra, or others create effects on the material plane? Do Gods need the Weave too? How did the Weave get created if there was no magic without it? If the Weave is just an interface, where is the origin of magic?

Via Divine power. No, gods don't 'need' the Weave, but they are restricted by it in FR... although Mystra has to be careful not to piss them off by controlling it.
The Weave was created by Mystra when she came into being. It's basically her divine domain.
Magic existed before the gods, and will exist after them. There's no defined origin to it yet overall, no 'Big Bang' that brought it in. That's not to say you can't introduce one to your campaign!

Do Psionics use the Weave? Do spelljamming races like Illithids or Gith make use of it everywhere?

They don't use it, but they are restricted by it. The energies are similar enough that limitations on the Weave tend to carry over to psionics... so high-level psions don't throw around divine-level magic any easier then spellcasters do.
Psionics may or may not work in some places, just like magic. It's a DM call. There are no official settings that say 'no psionics'.

Is "innate spellcasting" significant in lore or just a rule shorthand?

Rules short hand. It basically means 'this is a born magical being, not a plebe mortal like you, who had to LEARN to use magic.'

Metaphysics

I've seen references to Gods existing in multiple crystal spheres or campaign settings, so long as they have believers in each one. Why would that make a difference? If belief empowers/creates gods wouldn't a false god be impossible?

Without a divine spark, you've got no god. False gods basically steal worship and give it back. They don't have domains, have no divine spark, and are finite beings. They don't represent cosmic forces... they just pour faith in one side and out the other.

Where do gods exist? They have homes on out planes without regular rules of time/space, but it also seems that physical locations are important since they are in some way confined to crystal spheres in material space. How does that work?

What is a demiplane? Is it inside a certain crystal sphere?

Most gods exist in the outer planes, past the Astral Plane. Their homes are usually the final destinations of souls. Some cosmologies may have them living elsewhere, like the inner planes, or their own planes.
Their homes are tied to where they have worshipers. You may or may not be able to go from their homes to another Prime Material World, depending on the cosmology. If you use the Great Wheel, souls from all over the multiverse converge on those planes, so you can go to any Prime world from those planes, because all the gods of all the alignments dwell on the Great Wheel.
But in a homebrew, a god might only be served on one world, and only have connections there, with none to the greater multiverse.
In the baseline cosmology, connections are to the greater multiverse. If you go to the Seven Heavens from FR, you will enter it through a realm belonging to one of the LG gods who live there (Tyr, Torm, Ilmater, etc). You can then walk to the edge of their domain into that of their buddy Heironeous over there, and head on down to Oerth from there fairly easily... or wander around forever, never leaving the Triad's domain.

Demiplanes are simply pocket dimensions, usually made by powerful spellcasters in the past. There are actually spells out there that allow spellcasters to create demiplanes, and if they are old enough, they can get quite large.
Demiplanes created by deities are very small places for such entities, and so tend to be used only by demigods and such weaker beings, or as prison planes or storage places. It is far more likely they were created by mighty spellcasters or mighty non-gods for specific purposes and homes of their own. If those beings die, the demiplanes tend to degrade over time. They make great adventuring places, because they aren't that much different from instance dungeons in a video game. Whatever you want to be inside, can be inside one!

 

[tetrasodium]

I know that 5e has left most of this stuff out so far, and I know that a lot of this has probably been deliberately left out of most or all editions because its pointlessly analytic and rarely adds to the game. But I also know I'm not the only nerd who has asked these questions, so there must be at least hints where there aren't answers. I'm trying to put together the most sensible take that favors the most modern written lore whenever possible, but fills in the gaps with the next most recent thing, RAI. I've seen a lot of "its not supposed to be answered" around the internet. I'm not interested in that at all. I'm looking for the best universal theory on the dnd multiverse in 5e, that will definitely depend on older books.

5e great wheel

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Here are the quick, bottom lines that I have gathered so far about spelljamming, magic use, and the dnd universe. Please help me in my goal by correcting anything here or filling anything else in for it to be more comprehensive:


-Each rough solar system is contained in a crystal sphere, which is some kind of incredible barrier that even prevents gods from using their magic on other worlds. For example, Greyhawk had moons as a source of magic, FR has more traditional gods.


-Gods don't seem to be able to exist on multiple worlds unless they have other worshipers there.


-Magic in 5e is accessed through the weave, thanks to "the essence of Mystra".


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cosmology


Can you could travel from, say, FR to Greyhawk? Do the different campaign settings exist on the same material plane, or does each setting essentially have its own material plane? Is it all broad enough to contain a place for real-world Earth? Is there a sci-fi place without magic at all, where magic is impossible? Are there infinite places?


magic

If gods have any control over magic, why not just cut it off in certain places to further their goals?


What is "the weave"? PHB says "the essence of Mystra", and that "all magic depends on the Weave". I hear that its an interface mortal use to access magic, but why do you need spell components to do that, and how does a spellcasting focus alleviate that need? Why are some items consumed when casting the spell? What happens to them?


If you can travel between campaign settings, wouldn't a (divine) caster lose their magic when they leave their home crystal sphere, but maybe not a wizard? If the weave is everywhere, seems that wizards access it through study, while divine casters need their gods to assist.


How does a God like Mystra, or others create effects on the material plane? Do Gods need the Weave too? How did the Weave get created if there was no magic without it? If the Weave is just an interface, where is the origin of magic?


Do Psionics use the Weave? Do spelljamming races like Illithids or Gith make use of it everywhere?


Is "innate spellcasting" significant in lore or just a rule shorthand?


Metaphysics


I've seen references to Gods existing in multiple crystal spheres or campaign settings, so long as they have believers in each one. Why would that make a difference? If belief empowers/creates gods wouldn't a false god be impossible?


Where do gods exist? They have homes on out planes without regular rules of time/space, but it also seems that physical locations are important since they are in some way confined to crystal spheres in material space. How does that work?


What is a demiplane? Is it inside a certain crystal sphere?

A lot of these questions will need some thought on WotC's part if they do a spelljammer. Originally it was published before darksun & eberron, but both of those settings are violently incompatible with a lot of the baseline assumptions enforced/assumed to aencourage the question to be framed as is. in 4e they tried to just loredump parts of some other setting's lore & baselines into them to varying degrees & it went over much like room service delivering a live rat under your meal's silver cover dome thing.

 

[Aelryinth]

A lot of these questions will need some thought on WotC's part if they do a spelljammer. Originally it was published before darksun & eberron, but both of those settings are violently incompatible with a lot of the baseline assumptions enforced/assumed to aencourage the question to be framed as is. in 4e they tried to just loredump parts of some other setting's lore & baselines into them to varying degrees & it went over much like room service delivering a live rat under your meal's silver cover dome thing.

It is noteworthy that Spelljammer existed in Planescape (there's a module where they mention buying a squidship) as it Athas (there's an Athasian elf who runs between the upper planes as a merchant/courier).
Be that as it may, each world can be a part of the core rules or not. However, they did hint that planewalkers from other worlds had been to Eberron, which was technically not part of the Great Wheel.

 

[gyor]

Greyhawk has general magic, it's overdeity of magic is Boccob. You are thinking of the Dragonlance world of Krynn. FR has a mostly singular pantheon, unlike Greyhawk, which has 3 active competing ones (more like Earth)


That is correct, but they must have SUFFICIENT numbers to do so, if they are an existing god. This is considered expanding their inflence, and is generally regarded the same way you'd see a hobo setting up a tent on your front lawn.
False gods based on worship do exist in the setting.


Only in the Forgotten Realms, although using the term elsewhere doesn't hurt. The Weave, however, implies a Weaver, who is Mystra. In other worlds, magic might not need her control. The main reason behind the Weave is that both mortals and gods abuse the hell out of magic, and without the Weave there, it would all explode or collapse under their power-hungry fingers.

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Spelljammer is a way to travel from campaign world to world without leaving the Prime Material Plane. Leave the crystal sphere of your homeworld, go out into the phlogiston, sail to the new crystal sphere.
You can also do so by traveling through the Ethereal Plane, going into the deep ethereal and risking getting lost and nasty encounters; by finding the appropriate color pool in the Astral Plane (also daring encounters of soul-hunting outsiders and githyanki); or by plane-shifting to another plane, and then plane-shifting to the new world on the prime, if allowed to do so.
Technically speaking, a Wish or Interplanetary Teleport could get you to a new world, too.
Technically all game worlds are on the Prime Material Plane, but may be alternate dimensions within it, especially with house rules.
Earth exists and has been visited by both FR and Greyhawk natives in the past. There is a famous Dragon Magazine module where you go collect the Mace of St. Cuthbert, a divine artifact, from a museum on Earth. There's even elven jewelry on display there.
There are sci-fi settings with no magic at all, that have been visited by magic-users, and magic works there. Metamorphosis Alpha and the Starship Warden are classic tropes of this. So is Boot Hill, and characters often adventured from one to the other.
Where magic doesn't work at all? That is largely a DM call. There's no rule saying that characters with magic powers lose them in Star Frontiers or Star Trek. If you rule it so, then that's that. Can they DEVELOP them there? Without the classes, no.
Most planes are considered infinite, yet with borders, which is metaphysics at work. Paizo's Pathfinder world is set up like the real universe, without crystal spheres, for example. So, most planes you go on are infinite, but if you know how to, you can find the metaphysical border fairly easily.


Because the other gods would turn it back on to further theirs. Generally, removing magic destroys worship of the divine, because they can't answer prayers. Gods can get ornery if you try to do that to them. Balance!


It's a maintenance system for the magic of the realms.
FR is FULL of high level magic users. Seriously. Pretty much every major city has an archmage. Gods walked the lands, ancient dragons were everywhere, the elves had veritiable legions of archcasters, Netheril had post-30 casters, etc. They put massive amounts of pressure on magic, and the Weave was designed to keep the whole thing in place and working, without exploding and Bad Things Happening (like creating the Sea of Fallen Stars, and the Netheril Desert. Oops!)
Just think of it as another word for 'magic maintenance program', and Mystra sitting up there as the system overseer, and you're fine. Mechanically, it defines the limits on magic and how spells work, which is why magic is different between editions as the Weave gets a new operating system.


YES!
This was actually one of the things addressed in Spelljammer. You actually could buy altars that would allow you to connect to your deity in foreign spheres.
It also encouraged you to be a pantheist, or a planarist. If you were a pantheist, any plane that worshipped a god in your pantheon, you had spells. So, someone worshipping the Norse, Finnish, and Greek Pantheons could get spells in Realmspace via Tyr, Mieklikki, and Sune (Venus) respectively (and the Egyptian, Chinese, Japanese, Indian, and Babylonian Pantheons are there, too). A planarist of the Seven Heavens could get their spells as long as any LG god living in the Seven Heavens was worshipped there.


Via Divine power. No, gods don't 'need' the Weave, but they are restricted by it in FR... although Mystra has to be careful not to piss them off by controlling it.
The Weave was created by Mystra when she came into being. It's basically her divine domain.
Magic existed before the gods, and will exist after them. There's no defined origin to it yet overall, no 'Big Bang' that brought it in. That's not to say you can't introduce one to your campaign!


They don't use it, but they are restricted by it. The energies are similar enough that limitations on the Weave tend to carry over to psionics... so high-level psions don't throw around divine-level magic any easier then spellcasters do.
Psionics may or may not work in some places, just like magic. It's a DM call. There are no official settings that say 'no psionics'.


Rules short hand. It basically means 'this is a born magical being, not a plebe mortal like you, who had to LEARN to use magic.'


Without a divine spark, you've got no god. False gods basically steal worship and give it back. They don't have domains, have no divine spark, and are finite beings. They don't represent cosmic forces... they just pour faith in one side and out the other.



Most gods exist in the outer planes, past the Astral Plane. Their homes are usually the final destinations of souls. Some cosmologies may have them living elsewhere, like the inner planes, or their own planes.
Their homes are tied to where they have worshipers. You may or may not be able to go from their homes to another Prime Material World, depending on the cosmology. If you use the Great Wheel, souls from all over the multiverse converge on those planes, so you can go to any Prime world from those planes, because all the gods of all the alignments dwell on the Great Wheel.
But in a homebrew, a god might only be served on one world, and only have connections there, with none to the greater multiverse.
In the baseline cosmology, connections are to the greater multiverse. If you go to the Seven Heavens from FR, you will enter it through a realm belonging to one of the LG gods who live there (Tyr, Torm, Ilmater, etc). You can then walk to the edge of their domain into that of their buddy Heironeous over there, and head on down to Oerth from there fairly easily... or wander around forever, never leaving the Triad's domain.

Demiplanes are simply pocket dimensions, usually made by powerful spellcasters in the past. There are actually spells out there that allow spellcasters to create demiplanes, and if they are old enough, they can get quite large.
Demiplanes created by deities are very small places for such entities, and so tend to be used only by demigods and such weaker beings, or as prison planes or storage places. It is far more likely they were created by mighty spellcasters or mighty non-gods for specific purposes and homes of their own. If those beings die, the demiplanes tend to degrade over time. They make great adventuring places, because they aren't that much different from instance dungeons in a video game. Whatever you want to be inside, can be inside one!

FR has more Pantheons then you think. Currently It has the Faerunian Pantheon, the Mulhorandi Pantheon, Unther Pantheon, Dragonic Pantheon, Seldarine, Dark Seldarine, Orc Pantheon, Giant Pantheon, Qausi Yuirwood Pantheon, Dwarf Pantheon, Gobliniod Pantheon, Maztican Pantheon, Hindu Pantheon, Celestial Bureaucracy Pantheon, Loregiver/Al Qadim Pantheon, Elemental Tribes Pantheon, Urd/kobold Pantheon and a variety of loner monster deities. And in the ancient past the Grecoroman Pantheon, Celtic Pantheon, Norse Pantheon, and Finnish Pantheons had a presence in the Bakkar Empire. There might be others on unexplored continents of Toril or other Planets in Realmspace.