The Tunneler

The Tuneler is a Primordial creature. It lives in the bowels of the Underdark, tunneling the thick crust of the World Turtle's shell. The labyrinthine tunnel systems used by the drow, deurgar, and other Underdark creatures were created by the Tunneler. However, the Tunneler can sometimes destroy its own tunnels or change their courses, which makes navigating the Underdark a dangerous undertaking.