The Tome of the Undergrounds

Below the known world there are underground fortresses carved out of the earth by magic, by aeons of atmospheric agents or armies of slaves.
Once fortresses or huge uninhabited caves, these have become a melting pot of generally abject creatures, powerful and indubitably evil.
They are distinguished in the specific some of which here we will treat when possible of their history or at least of their simple discovery
A warning to adventurers: every dungeon is fraught with dangers as well as secrets. What at first glance may seem like an uninhabited cave could actually be a trap! Be careful and venture with trusted people. The treasures contained in those dungeons are large as well as the risks that must be faced to obtain them

Dimitri Sergjevich, First Keeper of Knowledge