In the final battle, Aang, Sokka, and Katara ambushed a Fire Nation ship.However, they did not realize that a massive fleet was approaching, which Agnaquila's warriors were unable to handle.Agnaquilla's only advantage is its location, accessible only by water.But General Zhao has acquired a spaceship that allows them to bypass the capital's defenses.This was Sai's design and Sokka helped him complete it.Therefore, his betrayal of the city of Omashu had a greater impact than he expected.The Northern Water Tribe prepares for a traditional battle, and Katara convinces Pagu to allow women from all tribes to fight.General Zhao outlines his other plan to Aihe, which is to kill Yue Ling when the Ice Moon Night siege occurs.Kula appears in front of An, warning him that the dagger General Zhao plans to use to kill Moon is nearby.

Aang, along with Sokka and Haoyue, went to stop General Zhao from carrying out this plan, allowing Katara to duel Zuko.Zuko sneaks into Agnaquiratul alone to capture Ann.In the forest, General Zhao saw two fish, one black and one white, swimming in a yin and yang pattern.Thinking it must be two spirits, he caught the white fish, the moon spirit, and prepared to pierce it.Despite Aihe's intervention, General Zhao impaled the fish, obscured the moon, and deprived the water escaper of his power.The battle situation changed, and the Fire Nation launched an attack, destroying the resistance.

In order to save the overall situation, An dedicated himself to the spirit of the ocean, allowing it to gain the power of the Avatar through him, transforming into a huge destruction monster, and immediately began to attack the Fire Nation fleet.Agnaquila destroyed the Fire Nation, and Zuko dueled General Zhao and easily defeated him.However, General Zhao tells Zuko that his entire mission is just Fire King Osai's way of inspiring Princess Azula.Zuko was crushed.Aihe eventually killed General Zhao, and his uncle and nephew escaped together.

In the finale, Agnaquila won the battle, but Ann was destined to become a wandering spirit of vengeance, roaming the world in search of the mate he could never find.Haoyue possesses part of the power of the Moon Spirit. She becomes the new Moon Spirit, ends her mortal life and saves the overall situation.With Katara constantly calling An back and saying she needed him, An returned to the group, although he felt guilty about the outcome of the battle and the damage caused.However, he was inspired by his friends to continue his journey and began to learn control techniques for other elements.However, the ending reveals that the attack on Agnaquila was merely a diversion so that Princess Asura could conquer the city of Omashu.The Fire Nation's conquest is far from over as Fire Lord Su Jin's comet is about to return.