It's just that if you don't get Blind, Berserk, or Subdue against strong units in school, you're doomed((( So I'm asking for advice on how to level up without relying on luck...

Against strong units, I would focus on maxing out light and defense, and in mini-artifacts, I would prioritize defense, initiative, and attack. Early in the game, it's desirable to get regeneration and build Colossus as quickly as possible.