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

I'm already so frustrated with this mission... The first time, I played it in my usual way – I always take my time, carefully developing and upgrading my heroes. As a result, by the time I had phoenixes, the Tear of Ashera, and had electrified all of Russia, Nikolai was sitting in the last castle with 42,000 dragons. After that, I started the mission again. This time, I didn't linger near the very first gate, which is guarded by a garrison of 600 zombies – instead, I figured out how to simply jump over the gate using this thing that looks like a portal, but it's for short distances. I forgot what that skill is called. Things started moving faster; I also obtained the dwarven treasures by "jumping" over the garrisons. But what's the point? This jerk, Nikolai, kept running away from the battlefield, and then, when I finally defeated him in the very last castle, I was told that the enemy hero was killed, and they gave me a whole cartload of artifacts – and he immediately appeared near my underground castle. And now, this pest runs around the entire dungeon, appearing each time with 40 fresh dragons. Even though he doesn't have a single castle of his own. Besides that, the game freezes from time to time during the turquoise faction's turn. So, what should I do? I already had phoenixes, but they died in one of the countless battles with Nikolai. By the way, all the important battles are fought by the redhead. My main elf is a bit crazy: he keeps trying to blast his own army with "Armageddon," so more of his own troops die than the enemy's. By the way, I fight all battles on autopilot; I don't have the energy to fight manually every time...