Rengar the Pridestalker

Sacrifice two other creatures: Riled 2 (If this
creature has no +1/+1 counters on it, put two +1/+1
counters on it and it deals damage equal to its power
to another target creature.)
As long as Rengar the Pridestalker has one or more
+1/+1 counter on it, it has: "Whenever this
creature deals combat damage to a player. Destroy target creature with the highest power that player controls."