Sakashima the Impostor

You may have Sakashima the Impostor enter as a copy of any creature on the battlefield, except its name is Sakashima the Impostor, it's legendary in addition to its other types, and it has "{2}{U}{U}: Return Sakashima the Impostor to its owner's hand at the beginning of the next end step."

As Sakashima the Impostor comes into play, you may choose a creature in play. If you do, Sakashima comes into play as a copy of that creature, except its name is still Sakashima the Impostor, it's still legendary, and it gains "{2UU}: Return Sakashima the Impostor to its owner's hand at end of turn."