Rough Rhino Cavalry

Two mechanics converge here, and neither behaves the way the body suggests. Firebending manufactures a burst of red mana every time this attacks, but that mana expires when combat closes, so the reward is locked inside the same swing that produced it. You cannot bank it for the second main phase; you spend it on the attack or you lose it, which pushes toward instant-speed pump and burn fired mid-combat rather than value held for later. Exhaust supplies the payoff worth pouring that mana into: eight mana, usable exactly once, to grow the creature and hand it trample for the turn. Eight is a number you rarely reach from lands alone in the turns when the counters matter, so the attack mana becomes load-bearing, covering a quarter of the activation the moment you commit to combat and leaving the rest to your open lands. The two effects fold into a single-combat loop, each attack chipping in toward the escalation that resolves in that same damage step. The once-per-game clause on Exhaust is what keeps this from being a repeatable overrun; it is a one-time detonation, a finisher you cash in when the board is already tilting your way and you would rather win now than grind another turn.