Simic Basilisk

Graft 3 (This creature enters the battlefield with three +1/+1 counters on it. Whenever another creature enters the battlefield, you may move a +1/+1 counter from this creature onto it.) {1}{G}: Until end of turn, target creature with a +1/+1 counter on it gains "Whenever this creature deals combat damage to a creature, destroy that creature at end of combat."