Gehenna, Queen of Shadows

+2: Return target creature card from a graveyard to the battlefield under your control with a Corruption counter on it.
-3: Destroy target creature, put a Corruption counter on X number of creatures where X is the destroyed creature's converted mana cost.
-12: Gain control of all permanents that have Corruption counters. They get +2/+2 and haste. Sacrifice them at the beginning the next end step.