Necromancer – “Assassination of the Ruler” [Campaign 3, Mission 4]

I don't know what the problem was here... I explored the entire map, and in the end, I had about 1500 skeleton archers, 25 dragons, 300 zombies, and 20 Death Knights... And with this army, I easily defeated the last hero... Of course, don't forget about the "Raise Dead" spell.