History Main / CastFromSanity

* ''VideoGame/{{Monark}}'' has the MAD gauge, which fills by a given percentage any time a character uses an Authority. If it hits 100%, they're afflicted with [[TheBerserker Madness]] and die after three turns unless it's cured.

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. See also CastFromMoney, which is ''less'' dangerous, but still non-traditional and ([[MoneyForNothing usually]]) not something you want to make a regular habit of.

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* In ''VideoGame/DontStarve'', using magic staves consume some amount of the player's sanity, in addition to [[BreakableWeapons bringing the staff one step close to breaking]]. Also, Wickerbottom's books have powerful effects but all consume massive amounts of sanity.
* The original ''VideoGame/BioShock1'' was 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 ([[SlidingScaleOfGameplayAndStoryIntegration much like the Splicers]] [[HeWhoFightsMonsters he defends himself against]]). This was scrapped, presumably because it would've limited the gameplay way too much ([[GameplayAndStorySegregation even if it would've made sense within the game's lore]]).

* ''VideoGame/PhysicalExorcismCase01'': SAN is the game's equivalent of MP for using skills, but if it drops to 0, the character will become insane and uncontrollable. Ectoplasm can be consumed to restore sanity.
* In ''VideoGame/LostDimension'', using PsychicPowers reduces the user's sanity meter.

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* Seems to be a common means of limiting magic use in ''TabletopGame/{{Fate}}'' games.

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* In ''Literature/{{Anachronauts}}'', magic spells destroy whatever they're written on when cast, and most human mages memorize their spells, meaning some brain cells get fried with every casting.
** Emily is/was CursedWithAwesome to be unable to memorize spells, and has to copy them and read them to cast them, retaining her sanity, and prefers utility spells, which means she has to think tactically in a way that tends to elude the other human witches (sanity loss) as well as the elves who trained them (not very creative).
* In ''LightNovel/HaremInTheLabyrinthOfAnotherWorld'', mana doubles as your SanityMeter, and the protagonist becomes suicidally depressed after spending most his mana casting his first spell. He later learns that it is common for dwarven master smiths to commit suicide after their first time creating a magic item, due to the same effect.

* Dreaming Lands' wizards from ''ComicBook/{{Die}}'' cast from memory. A wizard who was trying to rescue his children who'd been transformed into a hydra, cast a spell to unlock their cage then forgot the hydra was his children and killed it.

* The TropeMaker. Every spell cast in ''TabletopGame/CallOfCthulhu'' takes a toll on your mind. And increasing your Mythos knowledge (used to cast spells) ''permanently'' lowers your Sanity stat.

* Summoning demons in ''TabletopGame/{{Sorcerer}}'' has a high chance of lowering the summoner's Humanity (which acts as both a SanityMeter and a KarmaMeter in this game).

* In ''LightNovel/SlaveHaremInTheLabyrinthOfTheOtherWorld'', mana doubles as your SanityMeter, and the protagonist becomes suicidally depressed after spending most his mana casting his first spell. He later learns that it is common for dwarven master smiths to commit suicide after their first time creating a magic item, due to the same effect.