Blu/Blu 2 colorless, enchantment, At the beginning of each opponent's upkeep, that player reveals the top card of his or her library. If it's a creature card, the player puts the card into his or her graveyard and Shapeshifter's Marrow becomes a copy of that card. If it does, it loses this ability. It allows you to essentially steal an opponents creature, and they lose that creature card too. Was using in my blue fairies deck, but I changed it up, so I don't need it anymore. I hope this answers your question.