Uruk-Hai Cutthroat

Foul (At the beginning of your upkeep, put a -1/-1 counter on this creature. Whenever this creature is blocked by a creature, move a -1/-1 counter from this creature onto that creature.)
Whenever Uruk-Hai Cutthroat deals combat damage to a player, that player sacrifices a creature for each -1/-1 counter on Uruk-Hai Cutthroat.