anti-Necropolis faction

In a long game on a map where everyone has several foreign castles, Necropolis will overwhelm any anti-Necropolis faction (IMO).

Not in all cases. The game was very long, and I had 3 towns. The opponent had one, but it was an Elven town. My army was huge. When I finally met the Elven opponent, he defeated me. His archers attacked first, and my stack of liches was already destroyed. The hero cast antimagic on his archers, so I couldn't do anything to the archers. Then he cast haste on his mass, and his troops started moving twice, and then only mine. He basically wiped out my entire army with archers. I only managed to take out his ents.
It's almost the same with Humans. If you drag out the game, Humans are very difficult to defeat. There will be a lot of knights, and the hero's level will be high (resulting in high stats). Humans will also move forward first. They will be saved from all dangerous spells with antimagic.