What skills should Necromancers take when facing Orcs on a very large map?

Sure, you made a decent plan. But did you forget that the Orc will be leveling up "Suppression," and all my Berserkers, debuffs, and other abilities will be much less effective?
Also, I don't see the point in investing in "Education"; we reach level 30 without any problems anyway, and I think only one point in "Magic Affinity" is useless. If other skills were also leveled up, it would be a different story.
Why level up "Stone Skin"? It's not that useful, and it wastes an entire turn. I think "Sturdy Defense" is better.
By the way, I always take archer skeletons, but this time I'll probably take shield skeletons, mainly because of the Centaurs, and they also have a chance to stun. Skeletons deal almost half damage most of the time, and that damage is further reduced by the opponent's defense, so 20% from ranged attacks won't make much difference.

Added after 59 seconds
Ah, I understand, the bonus from "Education" gives a lot of additional stats, and by level 30, there will be quite a few of them.