Walkthrough tips, Discussion of Campaigns [Heroes 5]

Hmm... I started playing as the Dark Elves... What the heck is with this overpowered unit they put in the very first mission? He's level 21, and my level limit is 12!!! And it's obvious that he didn't level up at all – his stats are all between 1 and 3... What the heck is this? It would be okay if it weren't for the damage he deals, which is based on his level. He takes out 2 Hydras or 3 Shadow Witches with a single hit! %) What kind of tournament is this? Plus, he has an incredibly large army, much bigger than mine. Well, I won't dwell on that, probably I just lack the skill. But what's with the level? By the way, I managed to defeat this cheater. And that would be all, but the strongest of the remaining enemies came and finished off the remnants of my army, which no longer had any Hydras, Witches, or Furies, only 3 Grim Reapers, a couple of dozen Archers, and 26 Minotaurs. The enemy had full mana, 20 Grim Reapers, a bunch of Minotaurs, 63 Beasts, 34 Furies... In general, I have no idea how to proceed. In principle, if I try hard, I can...