Dengar

Bounty — Whenever a creature 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."