Avatar: The Last Airbender Season 1

In the world, there exist nations of the four elements: fire, water, earth, and air. The representative of the fire nation decided to conquer the other nations. The only one who can save the world and end the war is the Avatar, who can control all four elements. The responsibility suddenly falls on the shoulders of a twelve-year-old boy named Aang, who has to embark on a dangerous journey.