The strongest castle in Heroes of Might and Magic IV.

I agree with many points, perhaps even with all of them. But if the Necromancer is a human player (who has played the game before) and not the AI, and there are many neutral creatures on the map that can be used to increase the number of vampires, then it becomes very difficult to counter them. (In my opinion, the Necromancy aura doesn't protect against vampire regeneration). I try to cast a general buff on myself for the first strike, but the opponent removes it if possible.

It's not difficult to counter the undead with life magic. Even if the Necromancer raises a lot of vampires, they will all be affected by "Holy Word," which, if upgraded, will affect 10 vampires. Moreover, the second hero can throw "Holy Water." 5-10 vampires won't cause significant damage to a large army of light. Bone dragons are as strong as angels, but angels can be resurrected and can resurrect others. It's best to hide the angels from demons so that they don't steal mana. A tactician hero will allow you to do this.