The stages without the controllable main character should be RTS-style in order to make them less boring and frustrating to watch (as the AI is terrible as-is). Maybe allow changes to their formation or fighting style, or buy extra runes as the fight progresses?
Loved it! One critique: I don't like the drag/drop method. There should be number hotkeys for each piece. It would make it much easier that dragging all over the place!
 "Mighty Knight"){kind=icon}
 "pulse"){kind=icon}
 "Wonderputt"){kind=icon}