Tactics for Necropolis.

Yes, and here's another question. Everyone writes that you need to gather a lot of skeletons, but it takes 4-6 weeks. But if the outcome of the game should be decided in a maximum of 10-15 days.

if the outcome should be decided in 10-15 days, then you chose Necromancers for no reason) you need to play them on medium and large maps

when playing, you need to understand that in a direct confrontation, they will lose to many races, because while they have uber-warriors, they also have outright weak units, of which there are too many: zombies, ghosts, dragons, and to some extent, skeletons (unlike the first three, they are solid mid-tier units at their grade). You also need to actively use the transformation into skeletons (if you have extra money, buy heroes every week). There is also one bonus of the Necromancers that almost no one knows about, surprisingly (at least I haven't met anyone who knows it): hydras and dragons transform into dragon skeletons.