D&D 5E Help with ideas for a low-magic zone mechanic

[Sword of Spirit]

Some of you wanted more details about the campaign. The initial exposure to this region will be a party in a very long-lasting campaign visiting for (I expect) 12-15 sessions. They are all proficient in swashbuckling appropriate armaments, and most of the casters can also fight in melee, so they shouldn't feel like they can't contribute (the Lore bard would be the worse off, but he has a bunch of magic items he can use to make up for it). But the region is also part of the setting world building (my settings are persistent--they aren't just for a single campaign), so I'm not really taking into account the party in this campaign when it comes to designing the region. (If I were concerned it would be an issue, I just wouldn't have the magic portal drop this party there, and would run a theme adventure with new characters instead.)

So in other words, don't worry much about my party; it shouldn't be an issue. I'm more focused on the setting on its own.

 

[Auramancer]

Proposed Rule: All non-instantaneous spells require concentration. All spells that already required concentration also require the cooperation of another spellcaster, who also must concentrate on the spell.

In this environment, typical higher level spellcasters would probably stay away, just to not be at a disadvantage. This produces the reduced spell frequency and persistent effects. You might also extend this concentration requirement to magic items flashy functions, e.g. flametongue, sun blade.

 

[Sword of Spirit]

After reading through the answers and thinking about it more, I put together some ideas from it all, and here's something I think might work for me.

1) If a spell slot of 3rd-level or higher would be gained (as at level up) or regained, a 2nd-level spell slot is gained or regained in its place
2) Activating any "concentrated magic" (as defined in Sage Advice, see below) requires a check
-Spells: Spellcasting ability check, DC 10 + spell level
-Effects that indicate an ability score (including by derivation from a spell attack bonus or save DC): Spellcasting ability check, DC 10
-Effects that suggest no related ability score: 50% failure chance
On a failure, the action taken to activate the effect is wasted, but any spell slots or other magical resources that would be expended are not.
3) Always-on "concentrated magic" (like magical weapon +'s) is unaffected
4) "Background magic" (see Sage Advice) is unaffected, though creatures and phenomenon that manifest it are somewhat rarer in the region

This doesn't affect regaining other magical resources, like Sorcery Points, Innate Spellcasting uses, or magic item charges. This means that creatures with Innate Spellcasting have it better off than spellcasting classes, and magic items are often more functional than spellcasting.

Native casters will never know spells above 2nd level, because you can't learn a spell you don't have slots to cast. The way I do magic item creation means they will also hardly be able to create magic items. Visiting casters will keep their higher level spell slots and can use them to cast their higher level spells, but can't regain them after use--they just turn into 2nd level slots like for natives. This means they have a leg up if they come from outside and launch an attack, but once they've used up their slots they have no inherent advantage. (Natives that left the region would also be free of the issues.)

What holes am I missing in this? I expect there are things I haven't thought about that those rules might not entirely cover, and things I might not have thought through correctly.


Sage Advice Compendium (under "Is the breath weapon of a dragon magical?")
"[O]ur game makes a distinction between two types of magic:
• the background magic that is part of the D&D multiverse’s physics and the physiology of many D&D creatures
• the concentrated magical energy that is contained in a magic item or channeled to create a spell or other focused magical effect

In D&D, the first type of magic is part of nature. It is no more dispellable than the wind. A monster like a dragon exists because of that magic-enhanced nature. The second type of magic is what the rules are concerned about. When
a rule refers to something being magical, it’s referring to that second type. Determining whether a game feature is
magical is straightforward. Ask yourself these questions about the feature:

• Is it a magic item?
• Is it a spell? Or does it let you create the effects of a spell that’s mentioned in its description?
• Is it a spell attack?
• Is it fueled by the use of spell slots?
• Does its description say it’s magical?

If your answer to any of those questions is yes, the feature is magical." - Sage Advice Compendium

 

[Enevhar Aldarion]

Do like a lot of video games do and have something that permeates the air, the ground, the water, etc, that suppresses magical energy. Or something like a massive magic war happened in the past that drained the world of most of it's magical energy, so that now there is barely enough to power a low-level spell. Something like this would also prevent upcasting, so you would have to have some reason for characters to keep advancing and gaining slots they cannot use. Something that suppresses magical energy could also be so strong that it prevents most divine energy from reaching the material plane, so those casters would be limited too. Or that magical war somehow severed most of the ties of the material world to the outer planes, so that only a small amount of divine energy can get through. Maybe a part of their questing is to find a way to finally fix this problem and return full magic to the world. But if you are only doing a region or continent, instead of an entire world like this, the magic war turning the area into an almost magic-dead zone works better.

 

[Enevhar Aldarion]

As for your cut-off of 2nd level, there are so many important spells that come in at 3rd level, maybe instead of stopping at 2nd, adjust when they can acquire the spells. 1st level spells as normal, 2nd level not until 5th level in the class, 3rd level at 9th level in the class, and 4th and up never.

 

[Blue]

More ideas, pick one or more. Feel free to combine with my earlier list:

• Regaining spell slots requires spending a HD per spell level of the slot. Special addendum: slots may be brought back at a lower level.
• Spells above 2nd level require Concentration to cast, which will interrupt other Concentration. Spells above 4th level also require a Concentration check to complete, DC 6 + 2 * spell slot level. Failure means you lose the slot.
  • Alternate - failure means roll on the Wild Magic table.
• Casting also costs HPs equal to the slot level. (Either magical feedback or needing to spend your own essence to cast.)
• Casting more than 5 spell levels worth before taking a rest grants a level of Exhaustion.
• Concentration is difficult and you grant Advantage to all attacks and have Disadvantage on ability checks while doing so.
• Spells take up two slots. The second slot may be of any level that could cast the spell. Upcasting uses the lower of the two slots.
• All spellcasting except innate (some monsters) have V&S components. The somatic components require both hands.
• Spell attack rolls are made with disadvantage, save against spells are made with advantage.
• Spells may only be cast as rituals. If they do not have the ritual tag they may still be cast as rituals but consume the slot as normal.
• All dice used within a spell are shrunk one die size. A d4 becomes a d2. So fireball does 8d4 damage and Bless adds 1d2 to d20 rolls.

 

[Dausuul]

I'm working on a mini-setting in a part of a more standard D&D world. In this area, a supernatural effect has reduced the level of magic and increased the efficiency of certain scientific and alchemical processes, so we have a Three Musketeers sort of setting where smokepower/gunpowder is cheap enough to outfit armies, large ships with cannons sail the sea, etc.

I'm looking for an easy mechanic or two that will satisfy the feel I'm going for with regards to magic. There will be spellcasters from the region, but I would like spellcasting to be mostly limited to spells of 2nd level or lower, and I'm inclined to require a roll to successfully cast even those spells. I would like monsters and magic items with more powerful effects to still function, though they could be reduced in effect or reliability in some way. In addition, it should be possible for people from higher magic areas who visit this area to not be totally hosed in their magic, but neither should they be unaffected by the limitations of the area.

And I want this to work with as few rules as possible. Ideally, one or two simple rules that can create what I'm looking for.

I am assuming you intend this to be a place where PCs occasionally visit, rather than the main setting? If so, here is my proposal:

While in the area, you cannot recover spell slots of higher than 2nd level.

This would allow PC spellcasters to function in the area, and bust out their big guns when they really need them; but they would have to carefully ration their use of high-level magic for anything longer than a one-day trip.

 

[Dioltach]

Very simple idea: every spell has a (spell level x 10)% chance of failure.

 

[RangerWickett]

The ZEITGEIST adventure path had a similar explanation for why technology was coming to a fantasy world. One region about the size of France had been mostly stripped of magic, and a several-hundred-mile radius around it was a wild magic zone, and so industry grew up in the area.

We wanted PCs to be able to use magic on adventures, without the setting in that area having much magic. So the idea we settled on was that in the Dead Magic Zone, there's no local magic, but items from outside can carry magic for a while. It drains away within a few days, though. Innate magical abilities that refresh on a rest cannot refresh in the area, so a dragonborn gets, like, one use of their breath weapon and then has to get out of the area to regain it.

The exception to that was the 'infernal rebuke' power of tieflings, because they were created by the same curse that created the dead magic zone.

Persistent magical abilities - like a dwarf's darkvision, or a paladin's auras, or a fire elemental's entire being - would eventually be suppressed too. However, the party was never in either the dead or wild magic area for more than a few days, so we didn't have precise mechanics for this.

---

To keep things fast to play, without much complexity, maybe go with:

Weak Magic. It's not possible to cast spells above level 2 in the area. Cantrips in the area have an effect as if the caster were 1st level. When you cast a spell of level 1 or 2, roll an unmodified d20 against DC 10. If the result is 9 or less, you are unable to complete the spell, but the spell slot is not expended.

Magical Power Sources. If you have a magic item, you can draw upon the magic stored in it to cast a spell. This lets you reliably cast a spell of level 1 or 2 without a chance of failure, or to cast a cantrip at your actual caster level. After you draw upon an item's magic this way, the item loses its powers until it leaves the weak magic zone.

You can also attempt to draw upon a magic item to cast a spell of level 3 to 5, which requires an unmodified d20 roll (DC 10), like for normal weak magic rules. Even drawing upon magic items, it's not possible to cast spells higher than level 5 in the weak magic area.

Limited Ambient Magic. You cannot regain spell slots above level 2 in the area.