Vesuvan Doppelganger

Upon summoning, Doppelganger acquires all characteristics except color of any one creature in play on either side; any creature 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. Doppelganger may continue to copy a creature even after that creature leaves play, but if it switches it won’t be able to switch back.