The Beast, Deathless Prince

The design trick here is a self-imposed prison that the card hands you the key to. A 6/6 for four mana in these colors would ordinarily be a mistake, so the payment comes up front: six stun counters mean six untap steps of sitting inert before the demon can swing on its own. That is a brutal down payment, and most cards that ask it would leave you waiting. This one refuses to wait, because it wrote you a way to serve the sentence early. The cast trigger steals a creature, untaps it, and gives it menace and haste, so a borrowed body can go to work the turn you land the demon. The parole condition is where the design turns strange: the untap-and-draw fires when a creature deals combat damage to its owner. Swing that stolen creature back into the opponent you took it from, and their own attacker knocks a counter off The Beast and refills your hand. The engine rewards turning an opponent's creatures against them, whether by theft or by any other means of controlling a body long enough to point it home. Each such hit shaves a step off the sentence and pays you a card for the trouble. It is a card built around a peculiar loop: you win by making other people's creatures betray them, and the more that betrayal lands where it hurts, the faster the demon gets off the leash.