This has been upp before. I have a request. And that is that the most powerfull unit of each civilization should be spell free. The reason is that in the end when you've got your production up and plenty of cities all on auto-build offensive units, you don't want to go around and change production to something non-spellcarrying all the time. It's just so tedious and boring. That's why I never finnish my Chaos games. For the feel of the game I want to use greater demons. And since they're spell carrying and can't be used for invasions, I just don't build them in my core-cities, which are the only cities with production capacity to build any amount. And no matter which civ you play it's the same story.
-Tom