Volatile Magic

[MauveGnome]

I'm starting a new homebrew campaign and I'm playing around with ideas to make magic seem more volatile and unpredictable.

My idea is to introduce a Spell Success DC that all spells must pass.
The DC would be 10 - proficiency - spellcasting ability modifier (minimum of 1).
A fail would have to roll on Wild Magic Surge.
A natural 20 would turbo-charge the spell.

Has anyone had any experiences with mechanics similar to this? How did it work out?

Edit: No success DC would be required for cantrips or in areas high in arcane energy (such as a wizard's tower).

[Kane0]

So the spell still goes off with a surge attached?

What happens with chaos sorcerers?

[Greywander]

I've got something that might interest you. I haven't had a lot of opportunity to play with this yet, but the short experience with it I've had so far promises great risk for great power.

This was basically inspired by the spellcasting system of Warhammer Fantasy Roleplay. In that game, there were no limits on how many spells you could cast, but each spell carried a risk, both that the spell would fail, and that the spell might trigger "Tzeentch's Curse", basically a wild magic surge that could, in a worst case scenario, instantly kill you.

The document itself is kind of... haphazard at the moment, so you might just want to scroll down to the Wild Magic Surge tables and see if those interest you. If nothing else, maybe you can find some ideas to poach. But basically, the way spellcasting works is that you roll 1 to 4 dice, adding the results together, and have to beat a certain DC that depends on the spell level. Pass the DC and the spell casts (whether or not you trigger a wild magic surge), fail the DC, and it does not. Furthermore, you trigger wild magic surges on doubles, triples, and quadruples. The more dice you roll, the higher the chance of casting the spell, but also of triggering a wild magic surge.

A Minor Wild Magic surge (if you roll doubles) is usually inconvenient and temporary (most effects go away on a short or long rest, since you don't need to recharge spell slots anymore).

A Major Wild Magic surge (if you roll triples) is often permanent and/or harmful.

A Catastrophic Wild Magic surge (if you roll quadruples) has about a 50/50 chance of "roll a new character". On the plus side, you can also gain the ability to cast whatever spell were attempting at-will. You also risk never being able to cast any spell ever again, so there's that.

Anyway, here's (https://docs.google.com/document/d/1g9G0MwlSF3E6HFDJizb6lUH2gjC4PFSiV63dMjciMW4/edit#heading=h.pvx3flsro9py) the link to the document.

[blueb4sunrise1]

How about a fumble table.
Like opposite to a critical.
Upon rolling a natural 1 for example then second roll agsinst a fumble table with effects ranging from "lose your concentation miss a turn" to "spell backfires on caster and any group members in a 10ft radius. Causing all to die intantly leaving only the powedered remains and teeth" .

[MauveGnome]

How about a fumble table.


This was my idea for if the original plan didn't work at the table. I'd probably cherry pick 20 effects from the surge table.

[MauveGnome]

So the spell still goes off with a surge attached?

What happens with chaos sorcerers?

No, a failed spell just surges and burns the spell slot.

It would break chaos sorcerer so I'd probably have to remove it as an option.

[MauveGnome]

I've got something that might interest you.

Definitely interesting but a little over-complicated for my purposes.
There are elements in there that I can use for inspiration though. Thanks.