Steam Catapult

Repeatable creature removal stapled to a five-mana body would be oppressive at any speed, so the constraint here is brutal: it fires only on your own turn, and only before you declare attackers. That window is the friction that makes the rate work. You cannot snipe a blocker mid-combat, cannot answer a creature on the opponent's turn, cannot use it after attackers are declared. The card forces you to spend your own main-phase tempo destroying something already tapped, which usually means a creature that swung at you last turn and remains tapped on your upkeep, or one the opponent tapped for an activated ability. It rewards waiting to punish a misstep rather than dictating the board. The "tapped creature" requirement compounds the limitation: against an opponent who holds untapped blockers back, the catapult does nothing. This is the Portal design philosophy in miniature, where the introductory product line shaved interactivity off effects so new players would not be blown out by instant-speed tricks. Strip the timing restriction and you have a repeatable removal engine; bolt it on and you have a card that demands you set up the kill on your own clock, against a target that has already chosen to expose itself. The body is incidental: it exists to survive long enough to tap a few times, not to attack.