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

Hello. I need help; I don't know what to do. I have version 1.2 of the game. I can't complete the "Vampire Lord" mission. Here's what happened: I had 5 cities when I first encountered Nicholas. I entered the portal in the north of the dungeon and exited near one of his cities. He attacked me and won. His army was about twice as strong as mine. In particular, he had over 200 spectral dragons, while I only had 100 at that time. I replayed. But while fleeing from Nicholas, I captured the city near where I exited the portal and holed up in it. Nicholas didn't attack me and just wandered around nearby (scouting reports indicated he had "hundreds" of dragons). Fighting him was useless; he always defeated me. Then he suddenly disappeared and returned. And when he returned, he had 2,000 dragons! Naturally, I couldn't defeat him. I replayed again. This time, I captured his southern city as well. Then he holed up in his northern city and hasn't left since. I can't force him out. His dragons multiply like rabbits. I tried to build a powerful army, of course. But all I could manage with my 7 cities was a maximum of 400 dragons. He, on the other hand, already has 52,000 at this point. The more I play, the more they become. The other "population" in his army doesn't grow as quickly. The dragons in the mission have been defeated, I have phoenixes, the Tear of Ashi has been found, and the corresponding structure has been built in one of the cities. So, what should I do? Attached is a screenshot showing Nicholas's 52,000 dragons. In principle, if it weren't for them, defeating him wouldn't be particularly difficult.