The Fleshchanger

You may cast The Fleshchanger by sacrificing a creature with mana value 3 rather than paying its mana cost.

Creatures you control have Transfigure {1}{b}{b}. (They have {1}{b}{b}, Sacrifice this creature: Search your library for a creature card with equal mana value to the sacrificed creature and put that card into play, then shuffle. Activate only as a sorcery.)