The Avatar.

A world without its messiah is a world run down. Hundreds of years after the Avatars disappearance the world is slowly being overrun by the Black-foot, a clan full of dark energy users with the attention of taking the world. All hope seemed lost until the Avatar returned, a legend coming back from the dead to fix everything and right everyone's wrongs.

(Yes I know this is a lot like Avatar the last Airbender)