I completed the mission without any problems at all. This is what proper character development means:D
For those who are also stuck on this mission: I don't know about you, but what helped me was looting the dragon's lair at the very beginning of the mission. I got a bunch of artifacts and became a real terminator:D Of course, they bit my army pretty badly, but it was worth it.
Thanks again to everyone for the helpful advice :)
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