Knowledge (history, planes, or religion) DC 25:
The shattered ribs of Kazavon fell to the Qadiran scholarpriest of Irori, Vahahn, to protect. Traveling back to his home in Gurat, he meditated for months on how to hide or destroy the relic. Unfortunately, days of pondering the question led to a single answer: no power of mortals could destroy the artifact, and no mortal vault could be trusted to forever house such an evil. Accepting this grim truth, Vahahn sought a way to journey beyond the bounds of Golarion to find a reality where such vileness could be reliably constrained for all time.
Wise Vahahn traveled to countless worlds and impossible realms, and several of his journals documenting his travels eventually made their way back to Golarion where they are held within the Monastery of the Setting Star in the Zho Mountains. Soon after leaving Golarion, however, the priest realized he had been followed. The Golarionborn priest fought chain devils on the streets of Axis, escaped an ancient umbral dragon in Elysium, and treated with the cunning demon lord Abraxas in the Abyss, but in the end, Vahahn’s fate is uncertain. What is said, however, is that the Ribs of Kazavon now lie in the clutches of the merciless god Zon-Kuthon.
None know how or when the god of pain gained the artifact, but priests of the foul deity claim the relic lies within the vaults of Xovaikain on the Plane of Shadow, twisted into a mantle of bone fragments and hung alongside the eternally tormented soul of Vahahn. Whether the claims of madmen can be trusted, or if Vahahn and his unholy charge still elude Zon-Kuthon’s minions, none can truly be sure.