Fearless Pup

Send in a one-drop, then pay three mana mid-combat to swing a 1/1 into a 3/1: that is the entire pitch, and it demonstrates a mechanic that only pays out once you have already committed to attacking. The reward is gated behind the exact decision aggressive decks want to make anyway, so the incentive and the game plan point the same direction. First strike is what justifies the pump: boosting a creature that already lands its damage before the blocker swings back turns a modest body into one that trades up cleanly, running over anything with three or fewer toughness before its own damage ever registers. The tension lives in the sequencing. Boast can only fire on a creature that attacked this turn, so the +2/+0 has to be paid for after attackers are declared, folding the extra power into the same damage step; three mana is real, but the ability is built for a hand that has already emptied and has nothing better to do with its gas on a stalled board, which is precisely the position red aggro is happy to occupy. This is a mana sink stapled to a beater, designed so the cards that flood the board early still have somewhere to spend late-game mana. The build is unglamorous on purpose: one red mana buys an aggressive attacker now and a repeatable threat of first-strike damage later, and it asks nothing except that you keep swinging.