Please describe the skill build in more detail... And most importantly, against which faction are you building your character like this?

Against all factions. I usually play on a large map with 5 companions.
Well, ideally, if there are enough levels, I build the Necromancer like this:

Unstoppable Magic - as much as possible (I rarely level it above beginner)
Dark Ritual
Arcane Wave
Sense Elements
Logistics Expert
Luck Expert - Soldier's Luck - Magic Resistance - Lucky Spellcaster
Spellcasting Expert - Secret Knowledge - Fluctuating Mana - Wisdom (you can only take Wisdom)
Chaos Expert

This results in level 23. As a rule, I can't level up any higher.
But if we're dreaming...
Then also:
Summoning Expert - Master of Summons - Fire Warriors
This would be level 29. But I don't know what map would allow me to develop like that. So far, I haven't managed to get above level 23.

What I like about the Necromancer is that he has better mana than other Warlocks. And yet, Education is so lacking...