well, let's take paladins as an example. let's compare levels 6 and 7. three castles - a total of 51 paladins per week, which is quite realistic when the game is long, the map is rich, and the castles are already built. and 6 angels each. this is in addition to everything else that the knight has. the orc will have 12 wyverns and 6 cyclops per week. it's interesting who will be stronger...

Added after 4 minutes
Fireball

If the necromancer only buys low-level units from the new castles, taking into account that their growth rate may be very small due to the characteristics of these factions, then I have some doubts about how he will defeat the orc with anti-magic in a long game, even with darkness...