User blog comment:CrimsonWarden/Nazarick's NPC Level Count/@comment-26952857-20160916072620/@comment-27168967-20160917002609

I don't think the level cap would actually be confined to merely custom NPC. Anything that is not created through POP, summoning, mercenary system should be fair game. Also, it's probably safer to say that there are still some other special NPCs that are left unrevealed, particularly those that guard the eight floor being the prime suspects.