Insanity

Insanity is the secondary resource for Shadow priests, replacing Shadow Orbs and (to some extent) Shadowform.

It's shown as a bar below health and mana, refilled by certain abilities then used by Void Eruption to enter Voidform.

Generators

 * Mind Blast (15)
 * Mind Flay (12 with full duration)
 * Shadow Word: Death (15, or 30 if it kills the target)
 * Shadow Word: Pain (4)
 * Vampiric Touch (6)