Auto-translated
Tactics against a Warlock (also applicable against any opponent except a Necromancer and, in rare cases, a Wizard from the Academy):
Use more High Vampires, Archliches, and new Zombies. Place two equal stacks of Archliches in different corners. If the Warlock has dragons, take Death Harbingers and fill all remaining stacks with them.
Vampires attack and are resurrected, Archliches inflict plague, Harbingers eliminate dragons with their devastating grasp, and the Zombies' only task is to survive as long as possible.
The hero should have Master Dark Magic with Pain Lord + Master Enchantment with Undead Protection from Magic.
The main burden will fall on the hero, using 4th and 5th level dark magic.
If you're lucky and have Berserk and/or Subjugation, the Warlock is doomed. Primary targets are Lizards or Imps.
Otherwise, you can use either Unholy Word or Vampirism.
Unholy Word is straightforward.
Vampirism is cast first on Vampires, then on Zombies.