Consider using the Sanity score if your campaign revolves around entities of an utterly alien and unspeakable nature, such as Great Cthulhu, whose powers and minions can shatter a character’s mind. A character with a high Sanity is level-headed even in the face of insane circumstances, while a character with low Sanity is unsteady, breaking easily when confronted by eldritch horrors that are beyond normal reason.
Sanity Checks. You might ask characters to make a Sanity check in place of an Intelligence check to recall lore about the alien creatures of madness featured in your campaign, to decipher the writings of raving lunatics, or to learn spells from tomes of forbidden lore. You might also call for a Sanity check when a character tries one of the following activities:
- Deciphering a piece of text written in a language so alien that it threatens to break a character’s mind.
- Overcoming the lingering effects of madness.
- Comprehending a piece of alien magic foreign to all normal understanding of magic.
Sanity Saving Throws. You might call for a Sanity saving throw when a character runs the risk of succumbing to madness, such as in the following situations:
- Seeing a creature from the Far Realm or other alien realms for the first time.
- Making direct contact with the mind of an alien creature.
- Being subjected to spells that affect mental stability, such as the insanity option of the symbol spell.
- Passing through a demiplane built on alien physics.
- Resisting an effect conferred by an attack or spell that deals psychic damage.
A failed Sanity save might result in short-term, longterm, or indefinite madness, as described in chapter 8, “Running the Game.” Any time a character suffers from long-term or indefinite madness, the character’s Sanity is reduced by 1. A greater restoration spell can restore Sanity lost in this way, and a character can increase his or her Sanity through level advancement.
- Planes: Your ability to understand and know specific things not related to your native plane of existence.
- Alien: Your ability to understand and know specific things differing in nature or character typically to the point of incompatibility.
- Psionic: Your ability to understand and know specific effects which are psionic in nature, also used for opposing psionic minds attacking and defending.