The unfinished/natural area under the tower is home to stronger versions of the centipedes encountered earlier.
In the deepest chamber is the brood matriarch; a towering geopede with a rock-hard carapace and a maw large enough to swallow a person whole. After a tense fight, the party vanquishes the matriarch and explores the area. It is determined that the geopede burrowed in from the east – the resulting tunnel leads to a coastal cliff face.
As the party heads back to base, they are alarmed when a disembodied voice accosts them.