The Mist

At some point during The Last Battle, something triggered the detonation of The Mist. As the world split in half during The Cataclysm, a wall of dead-gray mist bled out across the planet, engulfing all in its path. Within the matter of a few hours, the outer planet had been engulfed in a wall of mist, reportedly killing or horrifically mutating all in its path. Anyone who managed to survive the Cataclysm, but was unable to be safely transported to the inside of the planet was lost to the mist. Even in present day, the mist clings to the planet surface. Any scouting parties who have ventured into the mist have never returned, so little is known about the mist today.