I don't know if you're against this sort of thing, but you can find videos of people beating the missions on Youtube if you want to see how other people do it.
Here's a video of Mission 2. All that guy does is basically summon Odin and beast on them, and it works.
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http://img267.imageshack.us/img267/2369/mythbattlers.jpg
http://img.photobucket.com/albums/v516/Sensui22/1248835958206.png