Brackwater Elemental

A 4/4 for three mana that disintegrates the moment it does its job: the catch is that "its job" is combat, the one thing a 4/4 body is built for. Commit it to an attack or a block and it sacrifices itself at the next end step, which means every swing is a one-turn rental and every block trades it away rather than chumps with it. The design reads as a deliberate inversion of the usual deal, where you pay extra for a recurring threat; here the recurring threat is the whole point, and the body's transience is what pays for the over-rate. Unearth is the engine that redeems the drawback: for the same three mana you bring it back with haste for a single exiled attack, turning the graveyard into a reload rather than a dead end. The interplay between the two clauses is the actual card. Cast it, swing once, let it die into the yard, then unearth it later for one more hasty 4/4 charge before exile takes it for good. It is an elemental built to be spent twice and discarded both times, a creature that reads less like a permanent than like two aggressive instants stapled to a graveyard. The whole structure rewards a deck that treats creatures as ammunition, where the question is never how long a body survives but how much damage it lands before it is gone.