Leonin Armorguard

A board pump stapled to a body, sold at the price of paying for both halves up front. Four mana buys a 3/3 and a one-shot team buff that resolves the moment it lands, and because the trigger reads "creatures you control" it always catches itself: drop it onto an empty board and the +1/+1 does nothing but inflate the new arrival to a 4/4 for the turn, drop it after committing a swarm and the bonus rewrites the combat math for every body you already control. The catch is that this is a creature without flash, so hard-casting it happens at sorcery speed, before combat. The opponent sees the pumped board before they declare blocks; there is no surprise, no stack-based trick, only a precommitted threat the defender gets to plan around. That distinguishes it from a static anthem, which would keep its bonus indefinitely while applying the same combat-math change the turn it arrives. What you trade for is permanence: a standing buff stays, this one evaporates at end of turn, so the design wants to be cast on the exact turn an attack pays off rather than held in reserve. It is go-wide green-white aggression compressed into a single permanent: the 3/3 sticks around as a blocker and future attacker, while the enters-the-battlefield burst is the part you spend the turn you find it, before the rest of your board gets to swing.