This explosive loop relies on Leyline Tyrant to safely bank the massive amounts of red mana generated by Sozin's Comet granting firebending 5 to your attacking creatures. Once you move to your postcombat main phase, that stockpiled mana remains securely in your pool thanks to Leyline Tyrant ignoring step-and-phase mana loss. You can then feed that exact mana directly into Aggravated Assault to untap your team and trigger an endless succession of additional combat phases.