From the introduction: Originally, there was very little on this level. When Queen Ryssa’s engineers arrived here, they began by constructing the entry chambers (area 364 and area 365). But as work progressed, the Queen’s viziers began to have horrible nightmares. This area was the final resting place of Xaqahandrar the Eternal Burrower--a legendary creature worshiped as a deity by burrowing creatures from all across the planes. Its body was part of the earth in these parts, and to excavate it for the purpose of glorifying a dwarf queen’s vanity, the dreams said, would call the very wrath of the earth itself against them all.