Sacred Haven of Debauchery

I also like to play without losing units.
In King's Bounty, vampires are overpowered. I remember fighting my old doppelganger on hard difficulty (the most challenging battle in the game, in my opinion). All my units died except for the vampires, and in the end, I not only won but also replenished their numbers by feeding on them until I had the original amount, thanks to some barbarians.