Bug Burrows. The natural, easy way to make themes for dungeon expanders would be to focus on types of living areas and work spaces: libraries and labs for magic-users, shrines and religious areas, etc. And there will certainly be some of those. However, I wanted to try something a little different to stretch the concept a bit… so I made a monster-themed expander instead.
As usual, you can connect this to any staircase or ladder, or in this case chutes and shafts, in other dungeons.