The mind hovers closer to insanity than most people want to believe. A strong psionicist can push a victim's mind just close enough to that border and show them what madness really is. Crippled by sudden visions and impulses, complicated actions, such as spells and skills, become much harder for the struggling victim for a short time. Discipline and psychic resistance will lower the effect of the spell, but even the undead are at least partially vulnerable to the grip of insanity. Mastery prolongs the effect, while knowledge of mental defense increases the likelihood of interrupts.