An ancient sorcerous gate, later excavation complex and immense black reservoir lie beneath the mountain north of Gren’s Hollow.
Layered construction
The oldest element is the Venerated’s black-green metal gate and the pocket realm beyond it. A later civilisation excavated around the prison, building service corridors, orb-lighting, work rooms, stairways and shafts in an attempt to study or exploit the power inside.
That civilisation vanished. By the time Jinpachi, Norri and Telson arrived, doors had rotted, medical tools had rusted and goblins had spent weeks searching the ruins.
The black river
Fissures opened by volcanic activity allowed the Mountain Prisoner’s substance to spread through the lower caverns. It formed rivers, basins and reservoirs that did not flow naturally. The fluid breathed, reached toward living creatures and stripped memory from those it submerged.
The inner prison
Beyond the gate lay a pristine mirror of the ruined hallway, an illusory study and a circular balcony under an immense stone dome. The lowest chamber held the entity’s liquid body and the skeletons of creatures taken across centuries.
Collapse
Telson sealed the escape tunnel while the mountain erupted. The entrance collapsed and the region began suffering sinkholes large enough to swallow people, cattle and houses. The entity remains beneath the mountain, delayed rather than destroyed.
Notes and record
This article combines campaign record, spoken lore and the mythic account preserved in the Earin archive.