Besides, necromancers have a huge amount of spells and summoning magic, which means that, if I understand correctly, it is advantageous for them to play defensively in battles with an opponent, and what could be better for this than a large number of resilient zombies?
One thing I don't quite like is the defense bonuses. After all, defense is one of the main parameters for a necromancer hero, which means that due to high defense, units already take little damage (compared, for example, to demons), which means that these -30% from skilled defense are not such a big bonus.
However, the prospect of fighting to the last is very tempting.