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D&D General The cosmology of your homebrew campaign

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Currently running with Eberron, so I'm using that cosmology there.

The homebrew I'm working on for future use will most likely use a modified version of the LevelUp/Zeitgeist cosmology:



Limit Break Dancing (He/They)
I wrote a cosmology for my campaign (at the time) called "The Fire Islands," back in 2008. You can find it here. Unfortunately the downloadable PDF is now showing a 404 Error, and I don't know what's up with that. It looks like the download link is broken? Perhaps @Morrus could point me to the new one?

The cosmology is based on the mythology of real-world Maori, which I'll copy below. (And thanks again, @Tonguez and @Nifft, for your help and feedback on this project!) It was originally written for 3.5 Edition D&D, so you'll notice a lot of pre-4E references and terms from that period in there.

In the beginning, there was only the Ethereal plane (Papa) and the Astral plane (Rangi). When the two were forced apart, light and matter (the Prime Plane) began to coexist between them. Thus, the universe according to the Fire Island traditions is organized with the Prime Plane wedged tightly between the Astral and Ethereal planes.

The Material Plane is organized by its four distinct layers of elements, in three layers. Earth and Water are side-by-side in the middle, with Fire below and Earth above (see figure). The elemental demi-planes (not shown), such as Dust, Rain, Mud, Steam, and Magma, form on the boundaries of these planes, and are evident in the material plane wherever two or more planes overlap (i.e., Magma lies on the boundary of Earth and Fire, and Rain lies on the boundary between Water and Air.)

The Plane of Shadow, the Infinite Layers of the Abyss, the Negative Energy Plane, and the Nine Hells are all demi-planes within the Ethereal Plane, and are collectively referred to as “The Underworld.” Buried beneath the world, these demi-planes are not visible from the Prime Plane.

Likewise, the Positive Energy Plane, The Celestial Realms, the Twelve High Heavens, and The Void are demi-planes within the Astral Plane, and are collectively referred to as “Rangi,” or The Sky Powers. They appear in the Prime Plane as the sun (Heaven), the moon (Positive Energy Plane), and stars (The Celestial Realms) moving across the sky (The Void).

Hawaiiki is the land of mankind’s ancestors, the birthplace of Tiki and the place where his children's souls live forever in peace. It lies adjacent to the Material Plane, but is accessible only by traveling through the Underworld. When a person dies, their soul is sent to the Underworld for judgment, and those who are found worthy are carried to the Ancestor Island in a canoe rowed by beautiful women. Those who are found wanting are forced to remain in the Underworld forever.

And here's my quick sketch of the cosmos:

Nowadays, my homebrew campaign is based heavily on Tribality's "Seas of Vodari" campaign setting, and combines a lot of these elements (especially the mythology and cosmology, but my players are FAR from uncovering any of that at the moment).
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Goblin Queen (She/Her/Hers)
My homebrew cosmology is a modified take on the World Axis from 4e, with some heavy inspiration from Chronicles of Darkness - especially from Werewolf the Forsaken, and the Neolithic setting from Dark Eras in particular. Also just a dash of Eberron’s Orrery.

At the center of the cosmos is the World. Parallel to the World is the Otherworld, which if you’re familiar with the Neolithic setting for Forsaken, is basically Pangea. It’s the home of the Fae, and the borderland between the material World and the various elemental planes (Earth, Water, Air, Fire, and Aether). The further you stray from civilization, the easier it becomes to cross into the Otherworld, and the “deeper” the Otherworld becomes. As you venture “deeper” into the Otherworld, you draw “closer” to the elemental planes as you become more sympathetically attuned to them. Go into a cave and you become more attuned to the plane of Earth. Go for a swim and you become more attuned to the plane of Water, etc.

Beneath the World (literally, underground) is the Underworld, which combines elements of the Underdark and the Shadowfell. Scholars of the planes debate whether this should be considered its own parallel world, or merely part of the Otherworld. And indeed, the relationship between the Underworld and the Abyss is very much analogous to that between the Otherworld and the elemental planes, so it could be argued that the Underworld and the Otherwold are one and the same, and the Abyss is an elemental plane. Though, since the elements that make up the World itself emanate from the elemental planes, this interpretation raises the somewhat disturbing question of what “element” emanates from the Abyss.

Beyond the World lies the Astral Sea. Within this Sea are suspended the Domains of the Celestial Gods - Sehanine, Erathis, Bane, Pelor, Kord, and Ioun. Scholars debate over the nature of these Celeatial Domains, but the most widely accepted view is that that they should be thought of as distant Worlds, each to their respective Gods as the World is to Melora; at once her home and Melora herself.

The Astral Sea and all the Worlds therein are believed to be contained within a crystal sphere. The stars are believed to be holes in this sphere, where it was punctured by aberrant beings from a Realm (or perhaps Realms) Far beyond the known cosmos.


Great Old One
I love the complexity of the Great Wheel as I love Planescape, but really liked the 4e addition of Shadowfell and Feywild, which are way more interesting than the Positive and Negative plane, although the plane of Shadows is really interesting in itself. After that, the only part which I dislike are the para- and quasi-elemental planes, there are phenomenons happening near the borders, but for me they don't really create new planes. furthermore, although the concept of calling the Astral Plane "the Astral Sea" is interesting, I prefer the original concept, especially since I like Spelljammer as well, which can give enough of a "sea" vibe. :)



In a nutshell...any/all of my AD&D/D&D (re: 1e through 5e) games use the Great Wheel as a base. I find absolutely nothing wrong or contradictory with having any other campaign world, with it's own creation, it's own elemental planes, it's own, well anything and everything.

This is why:

Q1, specifically The Demonweb. The reason that had such a profound "Ah-Ha!" moment for me was because in the Demonweb there are doors to other worlds. Not "large demi-planes"... WORLDS...like campaign settings. All located in the infinity of the Prime Material Plane. Like all other planes, it's infinite. So, it is, to me, obvious that all sorts of different "realities" would be possible here.

It is easy enough to just say "Yeah, you can't get to Darksun from anywhere because not even the gods can"...and that's ok. Why? Infinity. The gods in AD&D are VERY powerful...but not omnipotent or omniscient...not matter what they tell you. ;) The ONLY one who is this, is the DM.

So...who's to say that in the infinite void of the PMP, waaay off at "location Infinity +3,482" there exists a whole other contained 'cosmology'? Say... Aebyrnis? (Birthright Campaign, Cerlia is the campaign 'continent') It's history of gods, how it was created, how it all works, the Shadow World is specific to Birthright...but it does tell the DM to come up with their own 'actual' creation myth as the one presented in the setting is what "clerics are lead to believe at this point". ...and...oddly enough...this is just how the world works.

How does this jive in the Great Wheel? Easy: The DM says so. I know it's cliché and seems like a cop out, but the DM is the ONLY "omnipotent god" (so to say) of any D&D campaign world. Period. Not even the designers of the game can over-ride the DM in his/her own campaign.

So...having all these different "cosmologies" all fit perfectly fine within the Great Wheel. The PMP handles much of the heavy lifting, but...just like it, ALL the other Planes are also infinite...so, in a nutshell, 'anything's possible'.

For example, I play in a Calandia (Citystate of the Invincible Overlord) campaign. In it, the DM has decided to use the Demons/Sentinels, Arch-Magics, and To Hell and Back boxed sets. If you aren't familiar, the cosmology if those boxed sets is VERY different from that presented in the MM's and DMG. But... we still use the core AD&D 1e rules (even though it's... "For use with..." and not an official AD&D product). How do we merge them? Easy... Asmodeus, Zeus, Amaterasu, Fraz-Urb-Luu, Graz'zt...probaly exist, sure, but they are NEVER going to be able to find or show up in Calandia or it's "cosmology of planes, deities, demi-planes, etc". Unless the DM wants them to.

Bottom Line: The Great Wheel fits the D&D "Campaign Structure" perfectly. Almost like it was made to allow DM's to run any sort of fantasy campaign setting they want...each with their own rules, gods, planes, magic system, etc. :)

Of course, if you take EVERYTHING as literal...then nothing works. For any campaign. Even the ones that supposedly have "completely different cosmologies"; because they are still using AD&D/D&D rules...which have built-in assumptions...like "Clerics get their spells from gods" and "Magic spells are forgotten once cast". The second you say "Yeah, but in MY campaign, I'm using a spell-point system"...well, you might as well also just say "Yeah, but in MY campaign, there is only three gods; Good, Neutral and Evil and they were aspects of a single god who exploded itself on purpose...that explosion caused the formation of reality as we know it". But you still are "playing D&D"...in both instances.


Paul L. Ming


Victoria Rules
I use a variant of the great wheel, I suppose, though I never really think of it as such.

There's lots of different planes. Each element (air, earth, fire, water, magic) has one. Each alignment other than pure Neutral has at least one. Each major sentient species has at least one as an afterlife plane. Technically there's still the positive and negative planes as well though I think the last time I used either of these was about 1988. And there's a nigh-infinite number of relatively tiny demi-planes, along with - of course - the prime material and all the many worlds therein.

Tying most of these together are the astral and ethereal planes, along with a few other nodal connectors (e.g. a couple of nexus points, the infinite staircase, etc.).

Which leads me to a question as to how you lot rule on something: I've always allowed the spell Planeshift to take you from one prime material world/setting to another (e.g. Greyhawk to Toril) in the same universe, even though technically you're still on the same plane. Why? Because otherwise there's no spell that can jump you from world to world. Am I alone or unusual in this ruling, or is this how others handle it as well?


Great Old One
Which leads me to a question as to how you lot rule on something: I've always allowed the spell Planeshift to take you from one prime material world/setting to another (e.g. Greyhawk to Toril) in the same universe, even though technically you're still on the same plane. Why? Because otherwise there's no spell that can jump you from world to world. Am I alone or unusual in this ruling, or is this how others handle it as well?

That is indeed how I handle it as well, and the limitation requiring to have the right tuning fork is fundamental in keeping things under control there.

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