The Mimeoplasm

The Mimeoplasm {2}{B}{G}{U}

Legendary Creature - Ooze (CMC 5)
As The Mimeoplasm enters the battlefield, you may exile two creature cards from graveyards. If you do, it enters the battlefield as a copy of one of those cards with a number of additional +1/+1 counters on it equal to the power of the other card.