Sakashima the Impostor is a rare Legendary Creature — Human Rogue card from The List (PLST), collector number SOK-53. Current market price: $13.20, TCGplayer market prices via Scryfall.
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."