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

I just started playing the 5th installment. After reading all of this, I feel a bit sad. Since my Faidaen wasn't particularly focused on magic, but more as a fighter, everything was fine until this point. But apparently, as an alternative, I should try focusing on these two level 28 companions that were rescued from prisons in the 3rd installment. Otherwise, I don't even know how to proceed, even though I'm playing on Recruit difficulty. P.S. It's much easier to solve these problems in Heroes 4, when you have one specific fighter-tactician with the appropriate artifacts in your squad, and another one who is specifically a mage. And then, you can easily eliminate any enemy hero in the first few turns, and that's it.