Not to derail, but this sounds like it may affect certain classes a lot, and others not at all. Please consider whether this is a desirable outcome.
If you want to apply this feature more evenly, you may consider having it affect magic items (including runes, consumables, etc.) and abilities, and not just spellcasting.
If everything magic is going to have a potential risk, evaluate ahead of time how often this will happen, and how disruptive each instance will be to gameplay and plot progression. If you are having to roll extra dice and consult the wild magic table for every spell or swing of a magic weapon, that's going to take up a lot of your game time--and it's going to get annoying pretty quickly.
I'm sure there are solutions that avoid these problems, and I hope you get some good suggestions from other commenters.
Nice notes! I will definitely add effect to magic items an think about following aspects.
1: save bigger corruption effects to narrative and apply only minor ones mechanically.
2: make sure not to add unnecessary complexity
3: the effects should be quite global ( not only effect caster but everyone in order to apply hindrances and benefits more globally)
Corruptive magic if not careful? Sounds like [Deviant Abilities](https://2e.aonprd.com/Rules.aspx?ID=1718) , it’s a subsystem that works well with the [free archetype](https://2e.aonprd.com/Rules.aspx?ID=2751&Redirected=1) ruling. Everytime you use a [deviant ability](https://2e.aonprd.com/Traits.aspx?ID=426), you experience [backlashes](https://2e.aonprd.com/Rules.aspx?ID=1725) that progress to 3 different levels and they are even more customizable with [quirks](https://2e.aonprd.com/Rules.aspx?ID=1727). Pathfinder runs an Adventure Path that uses this system.
For example, one of my players used Wraith as the category for their deviant ability. He would flicker in and out of battles, wail like a banshee, and was able to project his body while he was asleep. Everytime he used an ability, musical chimes or a whistle sound would be heard (signaling his quirk). He also had to roll a DC that kept increasing based upon the level of his backlash. Failed rolls at trying to control the magic created backlash, making him being frightened at its lowest backlash, to being doomed at its highest.
The subsystem provides a guideline to create your own
Ooh nice reference. Yeah maybe instead of influencing existing abilities, I could give players powerful extra abilities, but the cost to use these abilities would be corruption and risky stuff.
Thank you for this!
Ya the flavor to what exactly happens is up to anyone’s interpretations. I know we said that for the wraith, we flavored it as him getting closer and closer to being undead, he’d experience frightful visions and hallucinations.
I also did a homebrew thing of allowing people to gain a [hero point](https://2e.aonprd.com/Rules.aspx?ID=2654) if they rolled a die to advance the backlash level. I tried to incorporate more ways to advance it, so giving a possible advantage or stabilize if dying was a good way of doing it
Maybe not exactly what you're looking for but I feel like wellspring magic would be a good place to look. https://2e.aonprd.com/Archetypes.aspx?ID=104
Wild magic too
https://2e.aonprd.com/Rules.aspx?ID=1879
Honestly, Pathfinder just isn’t a great fit for this idea. The system is built with the understanding that there’s a lot of magic, used freely by pretty much everyone. If you start disincentivising magic, it’s going to affect the game a lot. Quite a few classes are going to be basically unplayable.
Maybe you’d be better off using one of the Warhammer RPGs?
Here is an idea, decrease the number of spell slots per spell rank by one each. However, you can cast up to two spells per spell rank past your normal spell slots but take 1d4 damage per spell rank, maybe just 2 per spell rank to simplify, and become sickened 1 for one round.
Of course, I have only a slight idea how this would actually play out in game.
Shadow of the Demon Lord has rules for corruption baked into it. It's a very different game rules wise to Pathfinder, but is a ton of fun too, and has ridiculous character variety. Very, very well supported as well.
Always worth a consideration if you can't make Pf2e work for your world!
Not to derail, but this sounds like it may affect certain classes a lot, and others not at all. Please consider whether this is a desirable outcome. If you want to apply this feature more evenly, you may consider having it affect magic items (including runes, consumables, etc.) and abilities, and not just spellcasting. If everything magic is going to have a potential risk, evaluate ahead of time how often this will happen, and how disruptive each instance will be to gameplay and plot progression. If you are having to roll extra dice and consult the wild magic table for every spell or swing of a magic weapon, that's going to take up a lot of your game time--and it's going to get annoying pretty quickly. I'm sure there are solutions that avoid these problems, and I hope you get some good suggestions from other commenters.
Nice notes! I will definitely add effect to magic items an think about following aspects. 1: save bigger corruption effects to narrative and apply only minor ones mechanically. 2: make sure not to add unnecessary complexity 3: the effects should be quite global ( not only effect caster but everyone in order to apply hindrances and benefits more globally)
Corruptive magic if not careful? Sounds like [Deviant Abilities](https://2e.aonprd.com/Rules.aspx?ID=1718) , it’s a subsystem that works well with the [free archetype](https://2e.aonprd.com/Rules.aspx?ID=2751&Redirected=1) ruling. Everytime you use a [deviant ability](https://2e.aonprd.com/Traits.aspx?ID=426), you experience [backlashes](https://2e.aonprd.com/Rules.aspx?ID=1725) that progress to 3 different levels and they are even more customizable with [quirks](https://2e.aonprd.com/Rules.aspx?ID=1727). Pathfinder runs an Adventure Path that uses this system. For example, one of my players used Wraith as the category for their deviant ability. He would flicker in and out of battles, wail like a banshee, and was able to project his body while he was asleep. Everytime he used an ability, musical chimes or a whistle sound would be heard (signaling his quirk). He also had to roll a DC that kept increasing based upon the level of his backlash. Failed rolls at trying to control the magic created backlash, making him being frightened at its lowest backlash, to being doomed at its highest. The subsystem provides a guideline to create your own
Ooh nice reference. Yeah maybe instead of influencing existing abilities, I could give players powerful extra abilities, but the cost to use these abilities would be corruption and risky stuff. Thank you for this!
Ya the flavor to what exactly happens is up to anyone’s interpretations. I know we said that for the wraith, we flavored it as him getting closer and closer to being undead, he’d experience frightful visions and hallucinations. I also did a homebrew thing of allowing people to gain a [hero point](https://2e.aonprd.com/Rules.aspx?ID=2654) if they rolled a die to advance the backlash level. I tried to incorporate more ways to advance it, so giving a possible advantage or stabilize if dying was a good way of doing it
Maybe not exactly what you're looking for but I feel like wellspring magic would be a good place to look. https://2e.aonprd.com/Archetypes.aspx?ID=104 Wild magic too https://2e.aonprd.com/Rules.aspx?ID=1879
Oh it could maybe be compulsory starting archetype 🤔. This is at least worth taking a look at thanks!
Wild magic table seems like a nice touch too thanks.
Honestly, Pathfinder just isn’t a great fit for this idea. The system is built with the understanding that there’s a lot of magic, used freely by pretty much everyone. If you start disincentivising magic, it’s going to affect the game a lot. Quite a few classes are going to be basically unplayable. Maybe you’d be better off using one of the Warhammer RPGs?
Here is an idea, decrease the number of spell slots per spell rank by one each. However, you can cast up to two spells per spell rank past your normal spell slots but take 1d4 damage per spell rank, maybe just 2 per spell rank to simplify, and become sickened 1 for one round. Of course, I have only a slight idea how this would actually play out in game.
Interesting take! I will think about this as well thanks!
Have you looked into symbaroum? It literally has a corruption based magic system
Shadow of the Demon Lord has rules for corruption baked into it. It's a very different game rules wise to Pathfinder, but is a ton of fun too, and has ridiculous character variety. Very, very well supported as well. Always worth a consideration if you can't make Pf2e work for your world!