Sozin's Comet, Part 4: Avatar Aang

After Zuko is severely injured by a shot of lightning from Azula during their Agni Kai, Katara must face her alone. Sokka and Toph are separated from Suki while attempting to destroy the air fleet, and soon find themselves outnumbered. Meanwhile, fighting a losing battle against Ozai, Aang enters the Avatar State, and must finally decide whether or not Ozai must die in order to end the war.