Generally speaking, I don't think it's worth investing heavily in Chaos. Just take the basic Chaos units and the Fire Lord, and that's it. The Fire Lord doesn't depend on either magic skill or the level of skill development. If you get an education, you'll at least have some magic skills (maybe you can even get a stronger Fireball than a regular one:)), and you can get the Fireball without building a guild. You can also take artifacts for magic, but only if there aren't any artifacts that boost your army to take their place.