Here is the new version of my Old God theory:
He has ruled Draenor, a black stone rock world, engulphed by green fogs. But then the Titans came and imprisoned him, leaving Colossi to safeguard his prison. However his influence soon spread across the now full of life world. He slowly corrupted his guards into flesh, creating gronn and then ogres. Some however evaded this fate. Then he decided to destroy a mighty civilization of arakkoa called Apexis, who threatened his future freedom. He has taken control of their golems and destroyed them with their own tools. The mighty arakkoa civilization fell and he has used his powers to create an avatar of himself called Terokk in arakkoa form to take control of that mighty race, so that it wold never rise again. Soon his influence ran unchecked and he has even succeded to take control of the Emerald Dream of that world corrupting one of its keepers, the Raven Spirit Anzu.