Brambleguard Captain

Most anthem-style buffs hand out a flat bonus regardless of the source. This one pumps by the Captain's own power, which turns a modest 2/3 into a scaling engine: any effect that inflates that number (a counter, a temporary buff, another anthem pointed back at it) doubles as a multiplier on the +X/+0 it hands off each combat. Because the target can be the Captain itself, this is never a dead card: with no other creatures around, it aims the arrow at its own head, becomes a 4/3, and swings for four. Timing shapes it on both ends. The beginning-of-combat trigger resolves before attackers are declared, so a chosen creature commits to combat already swollen; but the trigger only fires on your turn and the bonus expires at end of turn, so none of this ever shows up on defense against the opponent's attack. The +0 toughness half keeps it aggressive rather than defensive: the target hits harder without surviving better, which rewards racing over grinding. Built as a mid-cost payoff for a red aggro deck, it wants a creature worth aiming at and, ideally, a way to make its own power balloon.