I have yet to try and play with Death magic realm, but when I do I'll keep in mind your tips on units. So far this game is going really good. I defeated all 4 wizards, but Sss'ra was strong enough to cast spell of returning so I need to go around and conquer his remaining cities. That shouln't really be a problem, cause he built a nice network of roads, so on Myrror it means only a single turn from one city to another.
I conquered innitial cities mainly using phantom warriors, but since I developed enough to produce longbowmen, they'd been my main weapon, supported by a hero or a few. I only added a unit of rangers later for the sake of pathfinding. Btw, it's funny that developers decided to put rangers in a nomad city, rather than elven
Alchemy proved useful at the beginning and I'm still using it a lot, though now I would've been able to afford 2:1 ratio anyway.