User blog comment:Pualover/Overlord Power Level/@comment-138.162.0.42-20150910182203/@comment-70.160.109.135-20150910210219

That Ainz may recognize the Eight Greed Kings really signifies they're strong. When you play an MMO and are actively into guild fighting, you keep track of rival guilds that are threatening or competative against you. There were probably hundreds or thousands of guilds in Yggdrasil, but Ainz would certainly recall the more popular or powerful ones.