Stoneyard Hunter

Dormant 8 (This creature enters the battlefield with eight Sleep Counters on it. Whenever an opponent casts a spell, or a creature you control dies, remove a sleep counter from Stoneyard Hunter.)
As long as Stoneyard Hunter has sleep counters on it, it has base power 0 and has hexproof.
When you remove the last Sleep counter from Stoneyard Hunter, destroy target creature an opponent controls.