The Necromancers are significantly stronger than what I saw in the Remix. The last one, Mordrakar, simply wipes out my entire army in the first few turns, going through the walls and broken gates. I don't have the artifacts that Greta had in the Remix. I discovered that if you engage the Necromancer in the field and not in the castle, the number of dropped artifacts increases dramatically.
And the cherry on top – the Necromancers arrive one at a time per week...
In short, it's basically impossible to complete the map on Recruit difficulty; what a paradox. Maybe, with time, I'll try it on Warrior difficulty – when the frustration subsides (after struggling so much to get the mentor for the Mage...). Or is the hero the easiest difficulty level after all?