"Flight to Salvation" - "Summoning the Dragon" [Campaign 4, Mission 3]

The game also wouldn't let me attack this priest. But I'm persistent, and after the 2nd or 3rd attempt, I managed to do it. It seems I directed Zehir not at the priest, but at the castle. If I had taken the army from Wulfsten and/or arrived with a full mana supply, I would have definitely defeated him. Of course, that would have ended badly, just like in the 5th mission of the 1st campaign of the original game. There, I broke through the garrison and captured the demon castle. Dwarves haven't mastered teleportation yet. I just asked if they would come to the surface. I didn't know that the priest couldn't be bypassed by dwarves either. Now I know, and I can calmly, without fearing a dwarf raid, go and get acquainted with other enemies.