I'm writing as an experienced Necromancer who fought against humans on the Empire map (Markel vs. Godric). And I won, but with great difficulty. The earlier you attack the humans, the better. Accordingly, the humans need to stall for time. The thing is that the Knight hero has combat stats, and the more "meat" he has, the higher the chances of overwhelming the Necromancer. The Necromancer's troops won't be able to handle the knights. Train Paladins – the more Paladins, the better. Cast Antimagic on them and charge! One strike – one stack of Necromancers is destroyed. Royal Griffons will take care of the ranged units. Only the Death Knights' Devastating Strike, which removes Antimagic, and the Phoenix with Elementals saved me. Therefore, the Knight's build: Leadership, Defense, Attack, Light Magic, Luck (it's important to take Dodge and preferably artifacts for Dodge).