By the way, I had the same thing happen to me in my first playthrough: Rutger appears and wreaks havoc. And there are a couple of other powerful heroes on their side, I don't remember who. I'm currently at that mission. What's funny is that Zephyr is level 20, and he hasn't been offered Chaos yet. He has one free skill slot; if he doesn't get it soon, I'll take Darkness. Otherwise, he has Air, Light, and Summoning, including Phoenix, Holy Word, Banish, and general Light spells, so it should be fine. He just has weak combat stats.