Avatar Aang, the world's last Airbender, learns of an ancient power that could save his culture from extinction. With the help of his friends, he embarks on a global quest to find it before it falls into the wrong hands and threatens to upend the peace they sacrificed everything to achieve.

The ultimate X-Men ensemble fights a war for the survival of the species across two time periods as they join forces with their younger selves in an epic battle that must change the past – to save our future.