Battle at the Moon Tower: You can't stop the ritual
Lynn and Lumilia couldn't believe it when they found that Yuko evolved into a third evolution monster. The power level of the monster was entirely different from that of humans and demis. Every evolution would increase their strength by several folds.
Since the dawn of the world, the monster's power level has been fixed at their evolution level, while the humans and demis base their power levels on the monsters.
Twenty thousand years ago, they called the F- and E-rank powerhouses a Warrior Level. D-rank and C-rank are powerhouses for a Battle Warrior, while B-rank and A-rank are at the Knight Level, which could somehow fight a third evolution monster.
Knight Level was the basic level of powerhouses in ancient times—a normal soldier at that time.