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

If you don't like the leveling process, replay the previous campaigns; they don't take much time.

That's exactly the problem – I've already spent a lot of time struggling with the "Emerald" campaign, and because of that, I don't want to replay it, but I feel like there's no other option.

And here's another question – has anyone tried completing a mission entirely with undead troops (after capturing their first castle)? Would that work?