The worlds of AtLA and MK merge, with all of their inhabitants playing each others' roles. My take on RexBlazer1's challenge from the forums. Has both my original intended crossover and the corrected, updated version. Rated T for violence.

When Shao Kahn's minions discover a means to invade the Avatar's world, he plans to absorb the souls of the realm to boost his powers dramatically, and conquer Earthrealm. When the Elder Gods learn of the plan, Earth's champions are sent to defend it...

An immortal warrior appeares and frees Ozai from his imprisonmet. The two then launch a new campaign to conquer the world. Aang, Katara and the others rush to stop them and are quickly joined by powerful new allies. Avatar/Mortal Kombat crossover.