Mogis's Warhound

The compulsion is the whole bargain here. Aggressive red has always paid for cheap stats by making the creature commit to the red zone, and this Dog doubles down: not only does it attack every turn it can, but whatever it bestows onto inherits the same forced march. You buy a 2/2 that swings into anything, or you pay the bestow cost to staple +2/+2 and that mandatory attack onto a creature you already control, turning a body you would cast anyway into a real threat while keeping the enchantment in reserve if the host dies. That second mode is the clever part of the design: bestow lets aggressive decks dodge the usual blowout of removal-meets-Aura, since when the host is killed the buff falls off as a creature on the battlefield rather than going to the graveyard with its target. The "attacks each combat if able" rider is the cost that keeps the rate honest, and it cuts both ways: it commits your own board to combat whether or not the math favors you, and it strips a creature of the option to hang back as a blocker. Note the limit on that compulsion: a "must attack" instruction never overrides a "can't attack" effect, so it cannot drag a Pacified or tapped-down creature into the red zone. It is red's recurring tension between tempo and control, written into a single two-drop that refuses to play defense.