Doppleganger

Enchant permanent card in an opponent's graveyard.

When Doppleganger enters, if it’s on the battlefield, it loses “enchant permanent card in an opponent's graveyard” and gains “enchant permanent put onto the battlefield with Doppleganger.” Return enchanted permanent card to the battlefield under your control and attach Doppleganger to it. When Doppleganger leaves the battlefield, that permanent's controller sacrifices it.