Auto-translated
Playing as the Necromancers? What could be simpler? -))
When playing as the Necromancers, it's important to upgrade Vampires as quickly as possible... you can ignore everything else if you face an unpleasant dilemma: either upgrade or do something else. 20-30 Vampire Lords + a Thanatos is a sufficient army to clear most of the territory (this can be assembled by week 3). Where the enemy is strong or doesn't restore life to the Vampires, Thanatos can independently resurrect the fallen. Skeletons accumulate naturally, BUT! they slow things down significantly, so I usually have a hero-courier following Thanatos, to whom I pass the skeletons or return them to Thanatos before battles where there might be difficulties.
Thanatos always has Earth magic, and you can quickly develop Knowledge to level 3-4, which gives you several revivals of the dead per battle. All that remains is to simply clear interesting locations, without missing anyone (skeletons need to be accumulated). Liches and Death Knights are usually best left in the city. They are strong, but if there are no battles with opponents expected, they are simply not needed. As a last resort, you can pass more Vampires from the city's growth to Thanatos in a chain - to make him even more effective. The main thing is not to lose them!!
Added 3 minutes later
In general, the best combination is Thanatos + Vampire Lords (30 is enough) + expert Slow + Liches (at least 10-15). These are real numbers that can be achieved by the end of the month, even on the maximum difficulty....
and the phrase "worthy opponent" - will disappear from your vocabulary for a long time