The combination of three skeletons is highly effective.
I've noticed in comments that people complain about skeletons being useless in later levels. They also said they pumped int.
I took the other route and got enough will that by the time the skeletons die, it's almost guaranteed that I'll have full MP, unless I was spamming spells at groups of monsters. Either way, skeletons only cost 160 and I have 585 MP. Even if things start hurting me badly, I can just spam heal, seeing how my MP recovers fast.
Draconian Necromancer seems like a thumbs up to me.