D&D 5E [Primeval Thule] House rules for spellcasting

[Tony Vargas]

Elves are supposedly good with arcane magic. They also live a long time. Making a lot of corruption rolls over their lifetime, an elder elf would more closely resemble a demonic being than an elf.

Drow had to start somewhere, right? ("Why do I have this strange urge to take up spinning...?")

Also, not sure what to do with cantrips. Like the Wild Mage, I don't want there to be a check every time a cantrip is cast, but on the other hand, slinging around fire bolts and light spells willy-nilly doesn't really fit the setting.

They could blow up in your face on a natural 1 like an old-school fumble, or just do 1 point of the same type of damage it inflicts every time you cast it.
You could track all the damage you inflict with a particularly cantrip and when it reaches a certain threshold, something bad happens.
Or, just learning a cantrip could give you some kind of permanent 'corruption' effect or 'flaw,' marking you as a caster, but be safe to use from then on.

 

[Ath'kethin]

I require an Intelligence save every time a spell is cast; DC = the spell level. Failing the save incurs Taint effects per the 3.5 Heroes of Horror Taint effects and follows that progression. For those unfamiliar: it causes physical deformities that increase in severity as more saves are failed, are easily healable/reversible early on, but become progressively more dangerous.

I like this setup because it makes magic dangerous even to high-level casters, and makes higher level spells much more dangerous to cast than low level spells, but also gives a fairly high chance of success so the players don't feel their characters are a chore to play/use.

I also only require this of humans. But I only allow human PCs, so thems the ropes. My players love it, so I guess I'm doind something right.

And I have no PC full casters; the only full caster class I use is a conversion of the Sorcerer from The Spider God's Bride (which is an awesome 3rd-party Sword & Sorcery supplement,and if you don't own it you should). I also curb available spells, along the same lines. Generally, magic is for villans and dabblers dabble at their own risk.

 

[Agamon]

The Spider God's Bride (which is an awesome 3rd-party Sword & Sorcery supplement,and if you don't own it you should).

Yeah, I picked this up on the weekend. Looks pretty good!

 

[Psikerlord#]

I was thinking to change the rule, from a just '1' on a d20, to instead a result equal to or less than the level of the spell. So, for example, a 9th-level spell triggers a surge on a 9 or less.

Oh yeah this is a very good idea! I might have to steal this. Excellent smithers.

 

[ChrisCarlson]

So, the Madness rules in the DMG look to have some of the basic frameworks that might fit what I want to do. It even has the three increasing severe charts to roll on. I think it's a good start anyway. I'll have to ruminate a bit more on it...

 

[Psikerlord#]

Yep I incorporated the long term madness table and madness flaw table into my dangerous magic table. There are some excellent madness/corruption tables in Heroes of Horror book too (as an earlier poster pointed out above).

 

[Hussar]

So, the Madness rules in the DMG look to have some of the basic frameworks that might fit what I want to do. It even has the three increasing severe charts to roll on. I think it's a good start anyway. I'll have to ruminate a bit more on it...

Primeval Thule actually has madness checks for spells.

Madness Saves: When a character is exposed to a creature or situation that threatens madness, he or she must make a Wisdom save (DC varies). Events that call for madness saves include:
• Encountering an aberration, undead, or extraterrene creature for the first time (DC 10).
• Seeing an ally defeated by anaberration, undead, or extraterrene creature (DC 10).
• Being charmed by an aberration, undead, or extraterrene creature (DC 10).
• Witnessing alien or unwholesome magic (DC8+ spell level).
• Exposure to an alien environment (DC10).
• Hearing or seeing a Great Old One at a distance (DC 13).
• Exposure to a profoundly abnormal alien environment (DC18).

I bolded the lines that are pertinent here. How you define "alien or unwholesome magic" is entirely up to you. I would certainly think that anything necromantic comes up. But, then again, you could make the argument for invocations (burning someone to death with hellish flames (who's to say that fireballs look pretty?) could certainly be a check. Popping into a Rope Trick? Extraplanar environment, where you hear the slitherings of unknown purple prose somethings just beyond the safety of your pocket. Anything that summons anything extra planar could be considered unwholesome (what's really the difference between undead spirits and fairy spirits, they're both taboo).

That, right there, would pretty much nip in the bud any PC caster. I'd probably, although I haven't looked at it closely, allow bards since the tradition seems pretty benign and most people like bards. As in people in the game world I mean. And, by and large, bardic spells aren't really big and flashy. I'd also allow any partial caster - but, still force the madness checks on any "visual" effects.

 

[ChrisCarlson]

I don't think it was the intent to have spellcasters making those checks against their own spells. But maybe that's just me.

 

[Hussar]

I don't think it was the intent to have spellcasters making those checks against their own spells. But maybe that's just me.

Even if it's not, which is fair enough, the fact that you're driving the rest of the party slowly insane is probably enough to prevent parties from having casters.

 

[Agamon]

I'm not sure watching someone burn is enough to drive a person mad. At least, not in the traditional sense. Maybe if "fireball" was a flying immolating demon that flew at the victim and then disappeared before coalescing inside him, slowly liquefying his insides while a deep ghostly laugh echoes around him. Even allowing reskinning the spell, that's a bit of a stretch...