For human, i say double crypt, double slaughter.
ghouls and fiends mix with frenzy and web
wagons, statues, destroyers, and a couple of aboms should be fine. just be ready to have 3 or more destroyers for enough dispel. (dispel is really needed against human).
if you insist on getting necros, get dark ranger as your second hero, and disease cloud. (silence is REALLY great against human, and disease cloud will kill priest mana and moonwells).
you can silence the priests, and pelt them with disease cloud...a little know tactic for undead is using disease cloud well. when priests are in disease cloud, it kills their mana because they are all trying to heal 1 hp to everything...this will give you enough room to send in skels while not worrying about them having too many dispels. as long as you necro wagon correctly (long long siege in their town), the AM brilliance aura won't regen the priests' mana quick enough.