From the introduction:
For one hundred years the Wizard’s Cabal has ruled supreme over magic in Blackmoor armed their Arcane Foci and Skelfer Ard's Scale of Magical Energy. But Raddan Goss has struck the first blow in the new struggle for magical supremacy and has taken from the Cabal it’s most trusted resource; they need you to get it back.
A Dave Arneson’s Blackmoor Dwoemer Realm High-Level Optional two round adventure for players levels 7-13.
This module is recommended for players who have previously participated in Episode 72: The Dawn of Goss and is the final installment in the series "What Lies Beneath..."
WARNING: This module contains UNTIERED encounters and is recommended for well balanced parties. Playing up is not recommended and can result in party death. Players enter at their own risk.