Arni Metalbrow

Most attack triggers pay off once and reward you for the swing you already committed to; this one recurs off every attacker and pays you to keep the swing growing. Any creature that attacks or enters attacking offers the option to spend and drop a smaller creature from hand directly onto the battlefield tapped and attacking. That new body then enters attacking too, which triggers Arni again, opening another to cheat in something smaller still, and so the chain runs down your curve until you run out of mana or descending mana values. The strictly-less-than clause is the whole shape of the design: it forbids sideways or upward loops and forces a top-down cascade, so the payoff lives in how your hand curves rather than how much mana you can float. Because the creatures are placed directly onto the battlefield rather than cast, summoning sickness never applies (they are already sworn to the attack), but the same directness means their cast triggers never fire; this is a combat cheat, not a value engine, and you are trading those triggers away for tempo. The berserker framing is honest to the function: the card converts a red aggro hand into one escalating alpha strike, where each new attacker is both a body on the board and the fuel that pays for the next one, provided the red mana and the descending curve are both there.