The Mithral Forge was a key component of the victory of the Dragonlords over the armies of the Titans. The dwarves that came across the seas with the Dragonlords discovered this deposit of mithral and adamantine in the central mountain range of the new continent. For more than a decade, the mithral and adamantine was mined and used to forge weapons, armor, and magical artifacts for the mortal armies. The Titan, Lutheria, decided that something had to be done about the mine. She formed a pact with the Fates, who used their magic to breed a terrifying cerberus snake. Lutheria unleashed this hound to destroy the forge and slaughter the dwarves.
After driving out the dwarves, the cerberus snake made a lair in the mines and began to spawn hundreds of death spawn. The Dragonlords tried to retake the forge, but they were repeatedly driven back until they were forced to abandon it entirely. For several centuries the snake watched over the ruined forge. However, a decade ago, some primordial thing from the depths of the Underdark emerged and killed it. The death spawn remained in the mine but, without anything to direct them, they retreated into the lower depths. Several tribes of troglodytes crept into the upper levels soon afterwards.