Dengar

Bounty — Whenever a creature an opponent
controls with a bounty counter on it dies, that
creature's controller chooses one —
•You put a +1/+1 counter on each creature you
control and gain 4 life.
•You put a -1/-1 counter on each creature that
player controls, and Dengar deals 4 damage to
that player.
"Go ahead. Try it. I've got nothing to lose."