Stover, although he does not fully explore or indeed explain it, handles it nicely.
Earth is much more interesting, and effective enough.
The greatest Actor the Studio has ever employed is Caine. Unfortunately, in defeating Ma'elkoth, Caine was stabbed through the spine and now, a cripple, is resigned to spending the rest of his life back on Earth as a Studio executive. Also back on the magicless Earth is the god Ma'elkoth, stripped of his goddish abilities because out of the Overworld, and retained as a sort of museum exhibit. He and Caine have become in an odd way almost friends, although each would still gratefully destroy the other. It's not giving much away to tell you that, after several hundred pages, Caine wins and Ma'elkoth loses.