This explosive combination relies on generating a massive surplus of red mana to fuel infinite combat steps. Whenever any player declares an attacker, Avatar Roku, Firebender triggers to generously add six red mana to your pool, a windfall that Upwelling safely preserves across steps and phases without fading away. You then channel that banked mana into Aggravated Assault to untap your creatures and grant yourself an additional combat phase. Repeating this loop lets you continuously send creatures sideways, continually triggering Avatar Roku, Firebender while Aggravated Assault keeps the extra phases rolling indefinitely.