How should I develop my units to defeat a Knight?

To mish-gun: in principle, you can finish the game if you want; I'm actually curious how you'll manage to get at least 120 units with just one castle and without diplomacy. Regarding the generation of artifacts, I've found the cursed ring, which is a hindrance to Necropolis, three times in the same location, and I feel like it's not random. However, I didn't like that the second castle is Academy, because they don't produce many melee units; the only good thing is that you can buy artifacts, and the additional spell doesn't necessarily have to be Dark Magic.