Dirius, the Vile Imperator

Whenever a player casts a creature spell, put a Vile counter on Dirius.
Remove X Vile counters from Dirius: Exile target creature with converted mana cost X.
Then, if that creature had power X or less, its controller loses X life.
Other creatures you control get +X/+X, where X is the number of Vile counters on Dirius.