Drums, drums in the deep.
The Underdeep was a series of tunnels and caves beneath Ginchar, traditionally used by pagan cults in generations past. It was home to a Black Iron Golem cache, which was activated by Tobijah Kruel.
The presence of the Black Iron Golems hinted that those pagan cults in the Underdeep were once worshippers of Xostheron and Akaerna-Sagai.
Kruel and his congregation had intimate knowledge of these caverns. It was in these tunnels that many of the Church's traditions began to take shape. Amaulthar was used as a guide through the passageways by Richard de Marmont.