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Well, I don't kill neutrals with summons at all, except for raising the dead, and only at the beginning. It's definitely not worth giving up on education for the sake of magic. Yes, there are a lot of good things there, but there are many alternative branches that give more useful things. For example, I don't think it's a secret to anyone that the undead have the worst troop stats compared to all races. That is, defense and attack skills are a priority. I won't even talk about Darkness; it should be taken by any necromancer hero. Luck is also a more priority skill than magic. Lords and warriors with soldier skills work wonders. I won't even talk about bad luck and magic resistance. And as for small maps, Kaspar helps us here, and we focus on war machines.
Yes, don't forget about the campaign AI. Education is needed in any case. I don't know about you, but I can get education in 8 out of 10 cases by level 23. Of course, not with any hero,)) but with those who have a predisposition for it.
In general, I vote for education.
P.S. If something is wrong somewhere, and you have tested it in practice, I will be glad to hear it. And in general, I welcome any criticism. Because that's how we gain invaluable experience.
P.P.S. I would only take magic in the late game against orcs; otherwise, we can forget about winning. And Defense doesn't give anything there; any orc stack destroys our unit, unless it's a Battle Mage...