Vesuvan Doppelganger

Upon summoning, Doppelganger acquires all normal characteristics (except color) of any one creature in play on either side; any enchantments on the original creature are not copied. During controller’s upkeep, Doppelganger may take on the characteristics of a different creature in play instead. Doppleganger may continue to copy a creature even after that creature leaves play, but if it switches it won’t be able to switch back.