I have to say, though, I WOULD like an Elemental version of Myrror. Perhaps a third faction, too, which is much more defensive / slow creeping than the other two.
ie. Whenever the faction moves into the main Elemental world, they drag part of their own world with them, slowly changing the land into the other world. This would, however, be pretty much a requirement, as their units take small (but noticeable) bits of damage whenever they're not in a corrupted part of the world.
It's ridiculously unlikely, I know, but we can all dream, right? =p
