Avatar: The Last Airbender: The Crossroads of Destiny

When Azula threatens Zuko and Uncle Iroh, Zuko decides to finally confront her. Uncle Iroh calls on his old friend Toph to enlist the aid of her, Aang, and Sokka in rescuing Zuko. But they are unable to stop Azula when Zuko joins her and the Earth Kingdom falls under the Fire Nation's power.