Talk:Non-Playable Character/@comment-49.145.174.82-20180205165627/@comment-168.122.149.13-20180206014432

I'm guessing you can have different types of spawn NPC in different locations. So, vampires and undeads for floors 1-3, Ice-type monsters for floor 5, and so on.

The higher leveled NPCs are either Customs or Mercs. That's cause in the game, summoned monsters are not permanent and will go away after some time. This changed in the new world in that summoned undead can be permanent if there's a suitable corpse. And reason Nazarick didn't go down is that it's composed of 41 whales and that the game's popularity didn't last long enough for it to go down.