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

[Sword of Spirit]

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.

Ideas?

 

[Ath-kethin]

You could ban full casters and spellcasting subclasses. You could simply state that spells of 3rd level or higher do not work (which effectively does the same thing).

Requiring anyone who wants to cast spells to do it through the Magic Initiate and Ritual Caster feats is a valid approach. I've done all of the above in campaigns before and it worked.

Just make sure anyone joining the campaign understands this ahead of time. This should be part of your recruitment pitch to potential players; don't even wait until Session 0 to drop this bomb.

If you're adding it to part of an ongoing campaign, blocking 3rd+level spells still works, but maybe give the casters automatic proficiency with your muskets or something to compensate. Then you only have to worry about them taking those guns with them when they're done with the area, and eventually they'll run out of bullets so it kind of solves itself.

 

[Bayushi_seikuro]

This reminded me at first of the high-/low-magic area ideas for GURPS.

I like your ideas of magic under 3rd level working, that powerful magic items still work but at reduced effect, and also the idea of either Arcana checks to cast spells (I'd give natives advantage maybe to cast) and I also like the idea that native casters to the area have ritual casting as a feat because they've adapted to the low mana.

Writing that reminds me also of the set up for Dark Sun. Since the planet with largely stripped of mana, if I recall right, you had two types of wizards: the preservers, who tried to be careful drawing life-energy from the environment when they cast spells, and the defilers who just let it rip and killed whatever remaining vegetation was around them - which also made it pretty hard to hide the fact you're the person casting the spells

 

[aco175]

You can have spells cast work at -2 or -3 levels. A fireball is cast as a 1st level spell dealing 3d6 fire or such. The problem is that the cheap, easy spells of 1st level are not gone. You could have some limits on the school as well with enchantment spells working at full power and evocation at 1/4 power.

 

[tommybahama]

In Faerun it's written into the lore. From the Forgotten Realms Wiki:

Dead-magic zones, collectively known as the legacy of Helm,[1] were areas of space in which magic ceased to function. They were one of the lasting effects of the Time of Troubles.[2]

Creation​

Most dead magic zones were found where The Weave had torn apart and left a hole.[3] The Church of Shar also developed several rituals such as the Rite of Unwinding, that could artificially create dead-magic zones, some of which would continue to allow Shadow Weave magic to function.

The party surely has never encountered this so you can say your area is at the edge of a magically dead zone so magic works however you want.

 

[Quartz]

I'm working on a mini-setting in a part of a more standard D&D world.

How much time are the PCs going to spend inside this area? Are they going to start inside this area? As a player I would not be happy if I were promised a low-magic campaign so chose a semi-caster over a full caster and the campaign moved to a standard magic area. (Or vice versa.)

 

[Shiroiken]

When you cast a non-cantrip spell in the area, make a spellcasting check DC: 10+(spell level x5). If you fail by less than 5, you may spend a higher level spell slot to cast the spell with no additional benefit. Otherwise the spell fails and the slot is spent. When casting as a ritual, a spell slot of the ritual's level must be available to the caster, which is spent upon a failed check (but still successfully cast), with the spell having no effect if failed by 10 or more. Cantrips cast in the area are treated as if the caster was 5 levels lower.

Cantrips will always work, making them the fallback for casters, but damage will be significantly weaker. Level 1-2 spells will probably fail about half the time, or at least require an upcast. Level 3+ spells will fail regularly, often needing an upcast slot. With all of these inhibitions, it's unlikely that there will even be a caster of 7th level or higher in the area.

 

[jgsugden]

If going for this concept, I'd tell spellcasters that upon entering the area, they lose access to many of their spell slots. While in the area their effective caster level for purposes of spell slots (as determined under the multiclassing rules) is either 1/4, 1/3 or 1/2 of their normal effective spellcaster level (rounded down). If you went with 1/2, which I'd recommend, an 18th level wizard has slots like a 9th level wizard. A 10th level paladin / cleric 2 would have slots like a 3rd level caster ([[10/2] + 2] / 2) rounded down to 3.

 

[Quartz]

When you cast a non-cantrip spell in the area, make a spellcasting check DC: 10+(spell level x5). If you fail by less than 5, you may spend a higher level spell slot to cast the spell with no additional benefit.

You could simplify this by reducing the DC by 10 for each slot level higher than the spell's level. So if you cast a Fireball (level 3) using a 5th level slot the DC would be 10 + (3x5) - ((5-3) x10) or 5.

You might want to cap the DC - a DC 55 check for a 9th level spell is a little OTT.

 

[Blue]

Some ideas. Pick and choose.

• Spells must be upcast one level to function. This upcasting does not increase anything else about the spell like it normally would.
• Spells that normally take an action take 2 rounds to cast. Rituals take an hour. Bonus action spells take an action.
• Concentration saves are made vs. a DC equal to the damage inflicted, not half the damage. (Still min 10.)
• Reduce all duration by half.
• When a spell is cast, you may not cast that same spell for 1 minute as the weave of magic is stretching in that shape.