Built before the First Blight, this thaig was named after Paragon Heidrun. It served as an important lyrium mining source for the dwarven empire, but was eventually overrun by darkspawn and abandoned.
In ancient times, an "incident" involving "creatures that wear the faces of the dead" disturbed the mining operations and warranted direct military intervention by the dwarven king himself. Centuries later, members of the Legion of the Dead would often visit the ruins. Once they encountered a rock wraith in an old mine shaft near the thaig. Another time, they found a former prison of an Archdemon below the thaig itself. It was filled with darkspawn corpses, which died while praying to their god.