New era.

I forgot to remove Retribution from the upgrade list; with -3 morale, it's a useless perk.

Added 2 minutes ago
So, it's quite possible to defeat Udun without hit-run tactics, without top-tier artifacts, and with a not-so-large army (by this point, you can easily gather around 60-100 more Paladins).

Thank you for the response; you are clearly much more experienced than I am. I'll try replaying, as I have saves from a week before and with 2-day intervals, so I think I'll have time to rebuild. I wanted to reach the Mentor level, but I somehow couldn't manage it consistently; I thought that overall, this kind of upgrade would be enough, even though I didn't have much luck with skill drops. And I tried to clear out the stacks with artifacts. Regarding teleportation, I understood immediately that it depends on the location of the troops in the hero's slots; I used it, but it didn't help me much. I don't remember if Resurrection was available or not; I focused on Arantir in battles with demons. It's quite difficult to get the Tome of Darkness; I think you saw who guards it. But overall, it's possible; I just didn't have time to get Arantir there, but I think he could have taken it without much trouble. As for the number of Paladins, it's debatable. I trained them as much as possible during the first month, when I had enough money, and after that, I did it consistently without missing any opportunities. Perhaps I didn't have enough Dweller stacks to increase the number of Monarchs, but I don't think I saw any more Dweller stacks with Monarchs there, only one. And I wouldn't dare give up Logistics, as I don't know how many more enemies there will be, and moving quickly is useful, at least to have time to farm more stacks or Dweller stacks. Thank you for the advice. And how many more enemies will there be after this demon?)) And what is the purpose of a hero in the Dungeon?