The party encountered the weakened pit fiend Avaxial in the lower levels of the dam at Skull’s Crossing. Rahab resisted the devil’s bargain and used his legendary intellect and magic to restore the dam’s damaged mechanism using Avaxial as a power source, thereby imprisoning the devil once more.
Per Rahab: “Avaxial is—or rather was — a general in the service of Dispater, the arch-devil who rules Dis, Hell’s second layer. His command encompassed twenty-nine legions of barbazu and at least three legions of cornugons with a detachment of osyluths. According to lore, Avaxial disappeared more than eight-thousand years ago, though whether on errand for Dispater or for some other reason has never been accurately catalogued. Indeed, there are several treatises speculating about his disappearance alone.”