Broodstar

Affinity does two jobs on this Beast, and they are the same job: the artifacts that shave the cost are the artifacts that set the body. In a deck full of cheap artifacts, the printed ten in the corner is a fiction; what you actually pay drops with every Ornithopter, every Myr, every Mox you control, and the same count that makes it castable for a fraction of its cost is the count that makes it enormous and evasive. That coupling is the elegant part and the fragile part at once. The reward scales perfectly with the board, but a board big enough to make Broodstar a one-sided finisher is a board the opponent has already had to answer, and a single sweep that hits the artifacts hits the body, the toughness, and the discount in one stroke: strip the count to zero and the flier is a 0/0 that falls out of the sky on its own. It is the showpiece of the original affinity mechanic's central idea, that the cards filling your hand and board can pay for the thing that ends the game with no separate ramp engine in between. Where the rest of the mechanic shipped efficient bodies and cheap utility, this one held out the payoff, a flier whose stat line is the literal census of everything else you committed. It rewards going all-in on artifacts and punishes nothing else, leaning entirely on whether the deck around it can keep the count high.