The Mimeoplasm is a rare Legendary Creature — Ooze card from Secret Lair Drop (SLD), collector number 1773. Current market price: $4.57, TCGplayer market prices via Scryfall.
As The Mimeoplasm enters, you may exile two creature cards from graveyards. If you do, it enters 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.