Tactics for playing against a Necromancer.

Zoltan is not the best choice against Humans and Dwarves. You should focus on mass light spells and use them on your troops. Zoltan's proficiency will be useless because you won't cast the same light spell twice anyway.

If you're going to develop light magic, don't forget to take Eternal Light; it would be a shame if your mass blessing from Zoltan is canceled out by a mass curse:(

As soon as possible, you can also take summoning magic to level up and achieve elemental balance.

Leadership should always be taken against Necropolis. To avoid too many problems from Zoltan's dark magic, take magic resistance, Master of Blessings, or Darkness Nullification from dark magic.