Sanity
Typically used with: Psyche.
In short: don't go crazy. There are those possessed of spiritual clarity strong enough to shrug off the bizarre, grotesque, and unnatural as though commonplace. These souls have hardened their minds against the unspeakable aspects of the universe.
Remain Sane
The Sanity skill is a person's primary weapon against horrifying situations or unnerving supernatural oddities: extra-dimensional beings, mutilated corpses, visions of the end of the world, twisted scientific experiments, or reduced-calorie fast food. Anything which threatens to break a character's understanding of reality calls for a Sanity check. The more horrifying the phenomenon, the higher the DL.
Resisting Spells
Some compulsory spells and illusory spells can be avoided with a Sanity check, for instance Cacophony and Insanity. In this case, you may add any points in Magic Defense to this roll. The mage makes a Casting Roll. You make a Sanity check. If your result meets or exceeds the Casting Roll, you elude the effects of the spell.