Recently made available by catastrophic earthquakes, the Great Alyrian Underground is a vast network of tunnels beneath the overworld of Alyria. Lord Agrippa himself has authorized expeditions to seal the opened passages to this treacherous place, to keep the population of horrific creatures from spilling out into the world. Hellbent Mountain is the exclusive passageway to the Great Alyrian Underground, but as the evils of the Great Alyrian Underground seep upward more routes may become evident. Home to some of the most evil creatures ever recorded, the Great Alyrian Underground is not for any curious adventurer.