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There's a mentor there; I didn't choose Dark Magic at the beginning either, but what prevents you from retraining?
If you take and rebuild 3 outposts, with an army focused on Dark Magic, it should be good. I had both Dark Cloaks, but for the most difficult battle against the dwarf, I used the Necromancer cloak with a bonus to Morale and Luck.
Another advantage is that you can prepare for the final battles, collect all the buffs on the map (and there are plenty), and discard unnecessary Leadership and Logistics skills, taking the most combat-oriented ones. Also, you have 2 sets of dwarves, and you can break his Luck with artifacts. I had this happen in that battle: http://c2n.me/3SRMuSk, http://c2n.me/3SRMy4k. I played it about six months ago, judging by the save date. It seems the computer didn't resist magic very well, so everything was fine. You can choose between the ability to subdue dragons and berserkers and breaking their spirit and luck. I also needed to discard Overseer and Experienced Commander for Deadly Misfortune, but I didn't bother.
You can weaken the undead with secondary heroes, leveled up under the mentor and equipped with the Sandro's Cloak, but I completely overwhelmed them.
If you take and rebuild 3 outposts, with an army focused on Dark Magic, it should be good. I had both Dark Cloaks, but for the most difficult battle against the dwarf, I used the Necromancer cloak with a bonus to Morale and Luck.
Another advantage is that you can prepare for the final battles, collect all the buffs on the map (and there are plenty), and discard unnecessary Leadership and Logistics skills, taking the most combat-oriented ones. Also, you have 2 sets of dwarves, and you can break his Luck with artifacts. I had this happen in that battle: http://c2n.me/3SRMuSk, http://c2n.me/3SRMy4k. I played it about six months ago, judging by the save date. It seems the computer didn't resist magic very well, so everything was fine. You can choose between the ability to subdue dragons and berserkers and breaking their spirit and luck. I also needed to discard Overseer and Experienced Commander for Deadly Misfortune, but I didn't bother.
You can weaken the undead with secondary heroes, leveled up under the mentor and equipped with the Sandro's Cloak, but I completely overwhelmed them.