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

Okay, I've replayed it five times now... Here are the scenarios: the first time, I really waited a long time, built up my army, and the game glitched with thousands of dragons – it didn't work. The second time, I did it very quickly, literally in the third or fourth week, with a half-destroyed army (after conquering a Castle, only a small part of the army remained, as the opponent still outnumbered me). I went down to the Dungeon, spent about a month just gathering some kind of army, came back to the surface, and Nikolai, with an army three times larger than mine, caught up with me – it didn't work. The third time, I built up my army for a little longer, but still spent much less time than the first time. I rushed into the Dungeon to collect these damn artifacts, and pay attention! Are you ready? Vlad, with a crazy desire to... well, I don't know what he wanted to do to me, chases after me with an awesome army that my army can't even compare to. While I'm running away from him in the Dungeon, a couple of weeks pass, and, lo and behold! I manage to outsmart him, I collect the artifacts, take the Phoenixes, and no one else dares to go into the Dungeon! I, happy, spend a couple of weeks clearing him out, gather a decent army by that time, and drag along another hero with the entire undead army from three Castles. We come out to the surface, and right away, on the next turn, Vlad, that jerk..., and Nikolai, from different sides, fly towards me and... they both stop exactly one step away from me. I fly to the nearest Castle captured by my second hero, and on the next turn, Vlad attacks me first. His army consists of 15,000 skeletons... the rest, I think, doesn't matter anymore. The battle is very short, and I'm starting the fourth attempt, rushing south on the second week, just attacking a simple hero with an army of a couple of hundred skeletons, and you can guess what my hero has grown to in two weeks. So, I started the fifth time. And what should I do? How should I even start? I... I don't even have the energy to be angry... this level has exhausted me so much. I used to breeze through everything, it was so easy, but this one... Hmm...