Eviigh'ir, Insatiable One

This creature costs {1} less to cast for each creature card in your graveyard.
Devour 2 (As this enters the battlefield, you may sacrifice any number of creatures. This creature enters the battlefield with twice that many +1/+1 counters on it.)
When Eviigh'ir, Insatiable One enters the battlefield, each opponent sacrifices a creature for each +1/+1 counter on it.