Necromancer – “Ruler of Erathia” [Campaign 3, Mission 5]

Veteran difficulty and Hero difficulty are completely different things in the campaign: I experienced it myself. Besides, I heavily leveled up Godric for the future and even took the "guardian angel" skill, so I had to fight the mages first, then start over with the strongest unit (I don't remember, it seems like a Rakshasa), then people appeared, and finally, I fought the Angels as the strongest unit. If you play without the "spiritual connection" skill, you might simply run out of mana.