Ranger - "Higher Vampire" [5th Campaign, 5th Mission]

I've encountered another problem. It's the final mission for the Mages, where Zephyr, Raeleth, Fayden, and Godric rescue Isabelle. I'm not sure if it's a bug or if I'm just missing something. When I defeat the Overlord the first time, I watch a cutscene, and then I'm not sure what to do next. Do I need to fight the Overlord two more times? My Godric almost died; he had a small army with clubs left, which was just enough to break through the wall with a catapult, and then he was about to be killed. What should I do? Should I change the game version? I have version 1.0, the official one, or is it supposed to be this way, but then I'll have to use cheats, which I don't want to do because I'm used to playing without them. Or should I wait for Zephyr to teleport everyone to the Silver Cities?

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