Speed factor.

I just played as Castle against Fortress on Tactician Corner 3 yesterday (yes, it was controlled by a "dumb" AI). I randomly chose fire and water magic, and +4 to spell power. I won on the first try, and without any difficulty.

It's really funny :) Now try playing the other way around. In the very first round, the archangels will fly in and attack some lizards, exposing themselves to a full stack of mighty gorgons. And I'm not even talking about magic. Would you be interested in playing against such an opponent?