Arni Brokenbrow

The Boast keyword's premise is a reward for committing to combat, and this berserker turns that commitment into a borrowed clock. The activation is deceptively humble: for one mana, once Arni has attacked, its base power becomes one plus the greatest power among your other creatures. On a board of small bodies that does little; alongside a genuine haymaker, it hands that number to a hasty attacker who can throw it at your opponent the turn it arrives. The design leans on a sequencing wrinkle. Boast is an activated ability you fire only after the attack is declared, so the power change lands mid-combat, before damage. That timing lets Arni present a modest 3/3 in the attack step and then swell past a blocker's math, or push through unblocked and suddenly hit far harder than its printed body suggested. Haste is what makes the loop urgent rather than incremental: there is no turn spent waiting to enable the boast, and the anthem-style theft becomes a same-turn payoff. What keeps it honest is that the change is to base power, not a stacking bonus, and it resets at end of turn: each combat you must attack, pay again, and rebuild the number, and the ability only ever reads a single creature's power rather than accumulating across the team. Arni is a red aggro engine that wants one large body in the wings to siphon from, repackaging the old idea of borrowing your biggest creature's number into a repeatable, attack-gated ability.