Illuna, Apex of Wishes is a mythic Legendary Creature — Beast Elemental Dinosaur card from Magic Online Promos (PRM), collector number 80991.
Mutate {3}{R/G}{U}{U} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.) Flying, trample Whenever this creature mutates, exile cards from the top of your library until you exile a nonland permanent card. Put that card onto the battlefield or into your hand.