You don’t need to go far to find RPGs that try to emulate that. There is one of my all-time favourites, Warhammer Fantasy, where usually you can decide to push for more mojo when spellcasting at the cost of triggering all sorts of unpredictable results (including the classic trope “demon shows up and drags the screaming wizard into Hell”). Most RPG systems that try to mimic this trope do so through rolls that trigger a host of unpleasant (and sometimes) lethal effects. Again, Warhammer Fantasy is (in)famous for its Chaos Tables, where spellcasters gain mutations and madness. GURPS has it backlash table. MERP used a system where spellcasting would bring the attention of the Enemy, triggering extra encounters (the same principle guides the “Eye of Sauron” rules of The Rong Ring today). Mage, the Ascension, a more narrative system, had all sorts of consequences available on its Paradox subsystems (mutations, madness, exile etc.). Call of Cthulhu, of course, drives its casters insane. 7th Sea (particularly the 1st Edition) has some VERY risky magic systems built upon narrative constraints (Porté, for example, will LITERALLY kill the caster if they merely open their eyes while teleporting). Riddle of Steel has magic that would age the caster. Star Wars has corruption rules (the Dark Side) for Force users. Ad infinitum.
I’m probably forgetting a lot of other games here and I apologize beforehand for that. However, I hope I gave you some context.
That said, I believe there is a certain confusion with all the approaches mentioned above. They mix two completely different themes – at least in my head – Risk and Corruption.
Risky magic is when it is totally or partially beyond the caster’s control. Often this is used through some sort of randomizer. The basic examples are magic systems where a bad roll (i.e. a fumble or critical failure) triggers (1) unwanted consequence or (2) some cost. The first option usually results in the spell changing some of its parameters (e.g., targeting different people, or maybe even doing something completely new… the latter usually by checking a table). The second aspect is often damage or some loss of resources (from the spell itself to other spellcasting capacities). Some RPGs impose permanent costs or limitations on its spellcasters – taboos, vulnerabilities, physical changes etc. Reign 1st offered some of the most interesting for their casters (I still have to check the 2nd Edition).
In my head, 99% of RPG magic systems that claim that magic is “dangerous and corruptive” are actually just talking about Risky Magic. Yes, Warhammer Fantasy is 100% here. Basically, these systems – to different degrees – insert random consequences and costs every time a PC tries to use their koolz powers. I loved those systems to death because in my head magic without any consequences (be it narrative or mechanic) is just superpowers with a different nametag. For me, magic requires a cost. It needs to have narrative or mechanic “teeth”. You can, of course, implement this approach to the degree that you (and your table) like. Some truly appreciate the danger with EVERY roll when magic is involved. Others prefer that a certain degree of agency be maintained for their spellcasters. Usually, the latter can be accomplished through options to cast safely or to channel more power, pushing the caster’s luck, or accepting some “Devil’s Bargain” mechanic. I’m fine with the spectrum, as long it helps the table to have fun and keeps magic, well, “magic” (that ‘je ne sais quoi’ that is essential for the flavour in some settings).
And before someone complains that they don’t see any problem with magic as superpowers… well, yes, you can have that, but – for everyone’s sake – just be CLEAR about it. There are VERY GOOD examples of magic as just cool extra powers, but you have to present them clearly, get everyone on board, and modulate your game’s fiction to support it (i.e., it must make sense). Otherwise, you will run into the “everyone must be a Jedi” problem (you can change it to “everyone must be an Elemental Bender”, “everyone must be a mage” etc.). Basically, if there are ZERO costs to magic, and if magic can accomplish a lot, then why isn’t EVERYONE in the party a mage? [There are some narrative and mechanical solutions for that question, but that is beyond this post. Some RPGs do it very well, such as 13th Age, FATE, and Avatar Legends for that matter. Some fiction remains fantastic even when using that trope and they are AWSOME, such as a good chunk of Sanderson’s Cosmere.]
Going back to magic. So, there is Risky Magic. What most RPGs call “magical corruption” is basically another way of saying that casting too much magic in those systems will fill your PC with weird physical and mental conditions, if it doesn’t kill you outright. Just that.
Do you truly want the trope of Magic as Corruption? Well, that one is harder. In my opinion, it is also a lot rare in RPGs. I normally identify two reasons for that.
The first one is about tone, limits, and common sense. When we are saying that magic corrupts your PC’s soul, we are basically stating that using magic is going to make you do a lot of awful or very dark shit. This can be off-limits for most tables (and I agree with that). Of course, if your table REALLY likes this trope, you are all adults and you know each other well enough to craft a good story (usually a tragic, dark, and very horror-based one) then by all means: give it a shot. But it is a balancing act. It is like enjoying (good) horror media: you have to be aware of boundaries, agency, and the self-awareness that you are creating/consuming this creative media for all to enjoy. Some RPGs did take that road. Most often, they present Magic as Corruption through narrative elements. A good example is magic rituals where the requirements of the spell are themselves horrific or the kind of thing that would give most people pause. Kult is a RPG that is famous for suggesting that kind of thing (although not to the degree that you would imagine… it is more of a reputation than a fact I would say). The OSR sourcebook Carcosa went in that direction by being very direct with its (otherwise d20-like) magic: all its summoning and spells require (a lot of) human sacrifice. There is no way around it. The games don’t glorify this element (thankfully) and it is quite clear on stating that sorcery is really bad and fucked-up.
The second reason why Magic as Corruption is so rare is that is a lot more challenging to provide mechanics for it. Yes, you can simply remove PC agency and make them do horrible stuff, but that is VERY boring. You have to preserve agency to the degree that, once shit hits the fan, the PC is aware that “Oh fuck! I did it”, instead of blaming this on the Dice Gods. Thus, the best corruption systems that try to tackle this used temptation as a hook to catch the player. Some really cool subsystems that can work as a template for Magic as Corruption can be found, for example, in Vampire: the Requiem and Werewolf: the Forsaken, particularly their Storyteller Handbooks and 2nd Editions. For example, pay attention to subsystems that require your PCs to keep human contacts to retain their sanity.
Now, you don’t have to go down such a dark road for Magic as Corruption. There are very simple ideas used in some RPGs that also work very well. Do you want one such example? Dark Sun, particularly the original AD&D 2nd edition. Wizards in Dark Sun can practice Preserving or Defiling magic. In this setting, magic drains life. If you channel it, life around you starts dying, usually starting with plants and small animals. There are ways to avoid the worst of it – Preserving – but the best mojo (i.e. the quicker and more powerful spells) are all based on Defiling – on sucking as much energy as often as possible. There you have it: a simple but awesome Magic as Corruption system principle. Yes, you can cast all the fireballs you want, but that will kill all the forest and fields around you… and also maybe deal some damage to your friends. So, what do you do? Again, the key in my opinion is to tempt the player with interesting mechanical options. THIS is Magic as Corruption at its core. You give the PC a choice, and you see they start to try to justify the lesser of two evils. The rest is for the table to enjoy. (Magic as Corruption in this case is also one of the “safest” to try at the table because it avoids the darker themes that we mentioned above).
On the top of my head, another awesome example was blood magic (maho) in Legend of the Five Rings 1st Edition: ANY character could plead with dark spirits to learn it, and once learned – oh boy – those spells were useful. But then, L5R triggered a set of corruption rules that were interestingly connected with the setting lore. It was almost like a death spiral. Too much corruption would eventually turn your PC into a monster (but not immediately). Meanwhile, everything in the setting would see you as a monster and try to kill you (even if you acted as a moral paladin). So, to defend yourself, you would probably use more dark magic. Brilliant!
One final example is Star Wars d6 (you know, the best one 😉), where any Force-sensitive character can immediately gain a Dark
Side Point if they use their powers in anger. The death spiral here was a LOT
faster… but that 1st Dark Side Point was “safe” to acquire. The
consequence? Most Force users in my campaigns were “tainted”. They took a bite
of the Dark and created wonderful narrative consequences to explore (besides the temptation of getting that 2nd Dark Side point… after all, the chances of falling to the Dark Side were “just” 16.66%).
Adding Magic as Corruption to your table (some very simple ideas):
So, my young padawan, do you want a feel of the Dark Side? Well, here are some very basic ideas. I hope they can spice your games (but talk with your players about this before starting on this road).
Side Commentary: This entire post was inspired by the idea of introducing what I like to call “creepypasta” lore or macabre secrets to an otherwise “normal” d20 game. The kind of stuff that would tempt people (and perhaps PCs) to do horrible stuff and then deal with that. That post is still coming, my loves. Wait for it!
DCCRPG: You already have all the tools you need here. Just introduce one simple enemy NPC who uses living defenceless victims to use Spellburn instead of damaging his own Ability Scores. LET THE PC SPELLCASTERS see the villain doing that. Let them know it is possible. This is the oldest evil magic trope: using sacrifices to power magic. However, when they decide to do that, instead of dealing ability damage (NPCs don’t have Ability Scores), explain that they are dealing damage and gaining 1 point of Spellburn per hit point (the victim must be either willingly or defenceless). If you want, go ahead and also add an element of risk: the PC can’t fine-tune the Spellburn (personally, I hate the fact that PCs can choose precisely how many points of Ability they lose for Spellburn). So, for this evil version, they must choose a weapon and roll damage (such as 1d4 for a dagger). The Judge is free to decide on a die for unusual circumstances (such as 1d3 per minute when bleeding a victim). The PCs don’t know how many hit points an NPC has (most 0-level people have 1d4 hit points). Better yet, the Judge should let the damage die explode. So, if you used a dagger (1d4) and rolled a 4, reroll and keep adding until reducing the NPC to 0 hit points (i.e. killing them). Keep tabs on who the PC kill. Potential consequences: shift their alignment to Chaos, consider them un-holy for most of the setting’s religions (at least those from Law and the Balance), and, finally, revenge! Did they sacrifice a poor gongfarmer? The dude has a big family, full of cousins, all hellbent on revenge! Or maybe they killed a thief with a pious sister who convinced a knight to create a band of inquisitors to go after the “devil magician” (i.e. the PC). Did they sacrifice a monster? Same principle: that beastmen was a member of a tribe! Don’t forget to make evil demon Patrons appear and offer to recruit the PC (asking them to do worse stuff and getting MORE enemies). Finally, remember that sacrifices in some cases CAN and SHOULD return as vengeful un-deads (or at least curse their killers). Watch how long the PC can go and have fun.
D&D B/X and its retroclones: use the Preserving/Defile idea of Dark Sun. Magic drains life. If the PC is using the Preserving, follow the normal spellcaster rules. If they decide to use Defiling magic, let the PC make a saving throw after casting. If they succeed, they don’t lose the spell. What are the consequences of Defiling? The original rules were complex, so here is my take: Defiling magic destroys all normal plant life in a 10’ ft radius per spell level. All plant life decays into ashes, and NOTHING grows there for one year (trees might die but still stand as dead husks). If more Defiling is cast within the span of 1 turn (10 minutes), add all the spell levels cast and DOUBLE the range of the damage. If there is no plant life in range, then all creatures (and plant creatures) within the 10 ft. radius suffer intense pain. More importantly, creatures with the same amount of HD as the spellcaster or less (or 0-level ones) suffer 1 point of damage per spell level (no save). Yes, this includes allies. Elves and druids consider Defiling a capital crime. Most religions concerned with life and nature won’t help, heal, or assist Defilers. Paladins will hunt them down, killing them ON SIGHT. The GM is encouraged to leave some mark on Defilers. Ideas: they smell of ashes or leave ashes in any place they stay too long, or maybe their hands start getting darker (as if burned) the more they use Defiling.
