Summarized List: Status Effects
An Insane creature can't think properly and isn't fully aware of what's going on, and may act unpredictably.
A creature can be permanently or temporarily insane. An insane creature can't perform any action trivially, and must pass a difficulty 10 Intelligence or Wisdom check (whichever is higher) in order to perform any action that would normally not involve a check. On a failure of this or any check, the creature acts erratically instead of performing the intended action. It might attack itself, shout random nonsense, or simply sit idle, muttering to itself.
A creature is insane whenever its net modifier for Intelligence or Wisdom is -5 or lower. This could happen as a result of any short- or long-term penalties to these attributes.
The counter for insanity depends on the source of the intelligence and/or wisdom penalty causing the effect. Countering that effect restores the creature's sanity, although it may not remember any of its experiences during that period.