All in all, Zack only learned that as the bases expanded, they gained more mana automatically. According to Roan, if they decide to summon something like goblins, they will be able to produce one of them every minute with the current rate of energy they obtained from the surroundings, probably from the land.
"I guess if the overlords expanded their territories until they managed to take over entire worlds, an army of this would be nothing for them," Zack thought. "If they are long-lived, it would make sense that they eventually would reach this far in their scale progress."
Zack had never encountered overlords who commanded territories spanning entire planets. This made him speculate that those overlords had likely made significant errors in their strategic choices and operational decisions. Such missteps could explain why Zack had been able to defeat them in the past, even when he was considerably weaker.
