History Main / CastFromSanity

* [[Literature/TheElminsterSeries Elminster]] from ''TabletopGames/ForgottenRealms'' has been like this since the Spellplague.

* In the ''IDW ComicBook/Ghostbusters'', four demons called ''The Collectors'' can be summoned to snatch people and trap them in a PrisonDimension at the cost of the summoner's soul and sanity.

* The original VideoGame/{{Bioshock}} was presumably going to have a variation of this as a mechanic: The player character would become more disfigured and more insane the more [[LegoGenetics Plasmids]] the player chose to use ([[GameplayAndStoryIntegration much like the Splicers]] [[HeWhoFightsMonsters he defends himself against]]). This was scrapped, presumably because it would've limited the gameplay way too much.

* In ''TabletopGame/MagicTheGathering'', this is the case for decks built around the keyword abilities Hellbent, Madness (yeah) and, to a lesser extent, Dredge. Sanity is represented by the cards left in your hand and in your library; an empty hand is unstable, an empty library is when a planeswalker is going to completely lose their mind. Madness allows you to sacrifice short-term sanity to play the card you're discarding cheaply; Hellbent denotes cards that gain an advantage when your hand is empty; and Dredge allows you to affect your long-term sanity to recur things from your graveyard.
* Most cards in the ''Necronomicon'' flash card game, with the notable exceptions of Mi-Go Surgery and some low-damage mundane weapons. There are a handful of sanity-restoring cards, as well.

* In ''TabletopGame/MagicTheGathering'', This is the case for decks built around the keyword abilities Hellbent, Madness (yeah) and, to a lesser extent, Dredge. Sanity is represented by the cards left in your hand and in your library; an empty hand is unstable, an empty library is when a planeswalker is going to completely lose their mind. Madness allows you to sacrifice short-term sanity to play the card you're discarding cheaply; Hellbent denotes cards that gain an advantage when your hand is empty; and Dredge allows you to affect your long-term sanity to recur things from your graveyard.

* In ''Anime/PuellaMagiMadokaMagica'', magical girls appear to use attacks that are CastFromHitPoints since the use of magic taints their soul gems. [[spoiler:The use of magic actually falls into this category. As a soul gem becomes cloudier, its user becomes more and more mentally unstable until she finally falls into despair and becomes a Witch Unfortunately, the nature of a soul gem means that its owner is essentially a lich, and has to use magic to keep her body functional. This coupled with the Monkey's Paw like effects of their wish makes the transformation all but inevitable]].

* In ''Anime/PuellaMagiMadokaMagica'', magical girls appear to use attacks that are CastFromHitPoints, as the use of magic taints their soul gems. [[spoiler:The use of magic actually falls into this category, since as a soul gem gets cloudier, its user becomes more and more mentally unstable until she finally falls into despair and becomes a Witch Unfortunately, the nature of a soul gem means that its owner is essentially a lich, and has to use magic to keep her body functional. This coupled with the Monkey's Paw like effects of their wish makes the transformation all but inevitable]].

* In the TabletopGame/{{Fate}} conversion of ''TabletopGame/EclipsePhase'' asyncs can boost their [[PsychicPowers psi-sleights]] by risking mental stress, which can lead to mental disorders as consequences. In contrast to the original EP rules, where asyncs risk their [[CastFromHitPoints hit points]] and go permanently insane in the process of gaining their [[WithGreatPowerComesGreatInsanity powers]].

The loss of sanity can be temporary - each spell pushing one closer to a [[RageBreakingPoint psychotic episode]] - or it can be permanent, with gradual SanitySlippage until the character can no longer function.

The justification for why the Sanity Meter takes a hit from using spells can differ. Maybe the {{Mana}} source is [[MindVirus tainted]], maybe the experience of using the magic [[GoMadFromTheRevelation is itself traumatic]], maybe it's a side effect due to [[BeingHumanSucks human brains being incompatible with magic]] - or maybe madness is simply the [[EquivalentExchange price you need to pay]].

Subtrope of PowerAtAPrice and TheCorruption. Sister trope to WithGreatPowerComesGreatInsanity, and PowerBornOfMadness. Compare and contrast with ThisIsYourBrainOnEvil.
In works where permanent sanity loss can be [[SanityStrengthening reversed by spending XP]], this trope overlaps with CastFromExperiencePoints.
Other non-traditional and dangerous ways to cast spells include CastFromLifespan and CastFromHitPoints.

* In ''Literature/NeverendingStory'', Bastian's [[spoiler: wishing power turns out to require sacrificing memories of the human world]].

* Goldmage's bluemages lose theory of mind as they use their power.

* ''TabletopGame/VampireTheRequiem'' has a few of the most powerful Theban Sorcery spells cost Willpower Points; once cast, the stat ''itself'' goes down. Characters can [[CastFromExperiencePoints spend XP to buy it back up to the previous level]], but until then they're essentially less able to expend mental and emotional energy. Interestingly, creating a new vampire requires the exact same expenditure on part of the vampire's sire. The setting details some sires who mass embrace too many, too quickly, and become emotional wrecks unable to hold themselves together.

* In ''Literature/TheReckonersTrilogy'', [[spoiler: Prof]] is very careful to limit the direct use of his powers, because of this trope. [[spoiler: He becomes increasingly arrogant and WhatMeasureIsANonSuper the more he uses it, unless he spends an extended time period avoiding use of his power. Most Supers in the setting don't know about this fact, and [[AfterTheEnd are by now beyond caring]]. ]]

* Every spell in ''TabletopGame/CallOfCthulhu''. And increasing your Mythos knowledge (used to cast spells) permanently lowers your Sanity stat.

** In Chaos Rising, you can find Chaos-corrupted wargear, which tends to be much better than standard equipment, but causes the character to fall towards Chaos and gain evil traits and abilities, along with determining the identity of the traitor in the team. Conversely, you can find equipment that restricts the character's stats, but reduces its corruption.

* ''VideoGame/MegaManBattleNetwork'': using the Dark Chips in BN4 and BN5 takes away your "sanity" from the invisible sanity gauge. Using them frequently enough will always make Mega Man be in the "dark" state, where he can get access to certain other powerful chips, but disables Soul Unisons and makes him unable to use "holy" chips like Sanctuary or Gun Del Sol. To get out of such a state, you have to do battles without using those chips, and you'll gradually turn better.

* The Alicorn Amulet from ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' corrupts its user with every use, though the user can return to normal by taking it off (and only by herself).