Bark-Knuckle Boxer

Expend reads your mana total, not your spell count, and this is the payoff tuned to reward crossing the fourth mana in a single turn. The body is a plain green 3/2, priced to trade and to attack into open mana, but the math shifts the moment your total mana spent this turn reaches four, whether that comes from a second spell or from one larger one. Indestructibility until end of turn does not save it from exile or bounce, and it costs no mana of its own; it is the reward for playing at the density expend wants, which is what keeps the ability from being free. The design question expend answers is how to make a green aggressive deck care about spending deep into a turn rather than curving out at two mana and passing, and this creature makes that abstract incentive concrete: clear the four-mana threshold and your attacker survives a block or a same-turn burn spell into combat. What elevates it past a vanilla beater is the bluff. Expend is a triggered ability, so crossing four total mana puts the indestructibility on the stack, where it resolves like any other trigger and can be answered before it settles. But a player holding up untapped lands still poses a question the opponent cannot resolve: the Boxer sits there as a known 3/2, and there is no way to read whether spending into it will save it from the block you were counting on.