1) A Warlock without mana is, to put it mildly, no longer a Warlock, as he strengthens his army rather weakly and probably doesn't have any abilities for his army either, except for Attack. The hero is the main striking force of the dark elves, as long as he has mana.
2) You can't quickly gather 200 golems, which means you played for quite a long time, and Dungeon is not as strong in the late stages of the game as it is in the early and middle stages.
3) In a long game, the Academy has the opportunity to create good mini-units, which significantly strengthens their army.
A lot depends on the battle tactics and the correctness of the moves. In general, having a good head on your shoulders and skillful hands always decides the outcome.