Kezzerdrix

A 4/4 first striker for four mana was an aggressively-statted body in its era, and the drawback is the design that pays for it: a self-inflicted four-damage clock that fires whenever your opponent has been cleared of creatures. The logic is pure incentive engineering. The card wants you ahead on board, and it punishes you precisely at the moment you have won the creature war, turning a stable lead into a race against your own life total. That reverses the usual relationship between aggression and safety: most beaters reward you for clearing the opposing board, while this one starts charging rent the upkeep after you do. The trigger is conditional on opponents controlling no creatures, so it can be switched off as easily as it switches on; a single token, a flashed-in blocker, or simply leaving one of their creatures alive defuses it. That turns a brawl into a strange negotiation where you sometimes want your opponent to keep a body on the table, and where chump-blocking can become a way to keep your own threat from biting you. The first strike matters here too, since it lets the body trade up in combat and stay relevant rather than just being a liability that wants to attack into open mana. The flavor lands the design: a rabid, twitching beast that hurts its owner when there is nothing left to maul.