Madness
In a typical campaign, characters aren't driven mad by the horrors they face and the carnage they inflict day after day, but sometimes the stress of being an adventurer can be too much to bear.
Various magical effects can inflict madness on an otherwise stable mind. Certain spells, such as contact other plane and symbol, can cause insanity. Diseases, poisons, and planar effects such as psychic wind or the howling winds of Pandemonium can all inflict madness. Some artifacts can also break the psyche of a character who uses or becomes attuned to them.
Resisting a madness-inducing effect usually requires a Wisdom or Charisma saving throw.
Curing Madness
A calm emotions spell can suppress the effects of madness, while a lesser restoration spell can rid a character of short-term or long-term madness. Depending on the source of the madness, remove curse or dispel evil and good might also prove effective. A greater restoration spell or more powerful magic is required to rid a character of indefinite madness.