Shapeshifter's Marrow

At the beginning of each opponent's upkeep, that player reveals the top card of their library. If it's a creature card, the player puts the card into their graveyard and this enchantment becomes a copy of that card. (If it does, it loses this ability.)

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6oa03d6ncppb1hfuc4jroe.