Tactics against Necromancers.

Against Necropolis, good morale is essential, and luck wouldn't hurt. Speed, and again, speed! Plus, good offensive spells are crucial on Expert difficulty. Don't forget about slowing spells. Berserk can be used effectively, but against whom depends on the situation. I think Blind is useful. Of course, Conflux and Tower are great against undead. But if the Necromancer has the King's Robe and Cursed Armor (which is relatively easy to acquire on large maps), then it becomes a problem...