What mixed hero class of the (Necropolis) faction do you like?

in fact, it's an archmage because he has a 20% effect bonus to all spells, and you can also choose a demonologist class

Added 1 minute ago
and also, the archmage doesn't necessarily need all magic skills; you can just take three skills of the second level, and you're already an archmage if there aren't other skills that are better to upgrade.