Fight takes place on an indestructible, endless flat arena. Shared universe rules apply, so "The Force wouldn't work on Miraak" or "Miraak has no Force resistance" doesn't apply. We will assume that magic/energy from both universes interact under the same umbrella.
Who takes it?
__________________ “The galaxy must experience the pain of death and the rapture of rebirth as I have. I will bring chaos. It is time for war.”