Isperia, Supreme Judge
Most punisher cards make the opponent choose between two bad outcomes; this Sphinx weaponizes the most basic action in the game, the attack step, and turns it into a tax the opponent cannot avoid if they want to win. The trigger fires on each attacking creature, not once per combat, so a wide assault hands you a fistful of cards. The defensive geometry is the point: it does nothing when a creature swings at a different player at a multiplayer table, and it rewards you for sitting back, holding up flyers, and daring the table to come at you. The "may" wording is load-bearing in a way the rate disguises, since it lets you decline draws when an empty library or an Underworld Dreams effect would turn the engine against you. A 6/4 flier closes games on its own clock while the card advantage piles up, but the four toughness is the honest counterweight: it dies to a respectable amount of removal and to combat math that a 6/6 would shrug off, so the player committing six mana to it is betting the engine resolves a turn before the opponent finds an answer. The result is a control finisher that asks the opponent to stop attacking, which is the one thing an aggressive deck is built to do.
