I wouldn't say it's that difficult for a demon to defeat a necromancer. 1. Imps steal mana => the opportunity for Berserk/Blind/Mind Control will be missed. You might object: what about the spiritual connection? Yes, it exists. But since the opportunity for the first application will most likely be missed, the necromancer might already be defeated. Well, if not, we'll rely on magic resistance. 2. The demon's initiative is significantly higher, allowing it to strike first, which is exactly what the demon needs. Savage Attack, but zero defense. So, there can be no defensive play. 3. It's worth developing Darkness, at least because of the mass slow/curse/disintegration ray. But you'll have to give up high-level spells. But if you have the Cloak of Sandro, you can use Darkness in its full capacity. Light is, of course, good, and mass Divine Power is very powerful, but a 2% chance of it appearing is not very serious. If it appears, that's good, but you shouldn't rely on it too much. I don't know what kind of defense it has with Readiness either. The demon is focused only on attack, and only the most desperate person will attack demons when Readiness is active. And only a novice demon stands still. Inferno has very fast units, and delay is often fatal for them.