Kedehern, the Annihilator

+1: Put an attrition counter on target permanent. Then, if that permanent has three or more attrition counters on it, destroy it.
-2: Destroy target permanent. Sacrifice Kedehern, the Annihilator unless another permanent has an attrition counter on it.
0: Until end of turn Kedehern, the Annihilator becomes a 5/5 Human Warrior creature with Attrition 1 that's still a planeswalker.