Duplicity ★★★★★

When Duplicity enters the battlefield, exile the top five cards of your library face down. At the beginning of your upkeep, you may exile all cards from your hand face down. If you do, put all other cards you own exiled with Duplicity into your hand. At the beginning of your end step, discard a card. When you lose control of Duplicity, put all cards exiled with Duplicity into their owner's graveyard.