[Bananadine]

Spells are the key. There are so many spells in this game--it takes a long time to get a good grip on even half of them. If you become accustomed to the use of that many spells, you will probably be able to think of several easy ways to obliterate any given AI army. And there will be good ways to counter whatever you might come up with, but the AI generally won't use those. It'll use the same sorts of chaotic armies in every situation.

If you aren't experienced enough with the game's spells to be able to use magic (and magical items) efficiently, then the strongest AI's will easily crush you with their numbers. If you are, then you'll have a pretty good chance of holding them off long enough to become strong, and once you're strong you will be invincible against them.