Gluttonous Lamia

Flying
Devour 1 (As this enters the battlefield, you may sacrifice any number of creatures. This creature enters the battlefield with that many +1/+1 counters on it.)
When this card attacks and becomes blocked, you may pay {4} and remove Gluttonous Lamia from combat. If you do, exile blocking creature and put a +1/+1 counter on Gluttonous Lamia.