Brainstealer Dragon
Theft has always been black wearing blue's clothes: exile the top of an opponent's library, cast what you find, and shrug at color-screw with mana of any color. The end-step impulse is generous enough (every opponent, every turn) that against a full table it hands you a stolen grip's worth of spells. But the second ability is the one that reframes the card. Any nonland permanent an opponent owns that enters under your control costs them life equal to its mana value: no life gained on your side, just their total shrinking. That folds two effects into one body. Effects that pull an opponent's permanent onto the battlefield under your control have historically been card-advantage plays; here they become a life-loss engine. Take a rival's fatty and you have not merely denied it, you have knocked six or eight or ten off their total for the privilege. The 6/6 flying body keeps the theft engine on a clock, so the card does not durdle while it accrues value: it closes on its own timeline and taxes anyone whose permanents it borrows. The design keys off high-mana-value permanents, so the life-loss scales precisely with how expensive the things you appropriate are; a slower, greedier board just makes each acquisition hurt more. What looks like a splashy top-end finisher is really a control-and-punish package welded to a dragon.
