From PathfinderWiki

Rithayn is a mysterious ruin buried in the mountainous slopes of Phlegethon, Hell's fourth layer. It predates Asmodeus and devilkind's arrival in Hell.1

Rithayn was discovered millennia ago when a damned soul scraping away at Phlegethon's slope uncovered a curve of darkened steel. After millennia of slow, ongoing excavations a pyramid of spiked metal has started to emerge from the rocky slope.1

The structure itself seems to have been built long before devilkind ever arrived in Hell. Belial, the Archdevil who rules Phlegethon, often visits Rithayn to contemplate the meaning and opportunities of this mysterious structure.1


  1. 1.0 1.1 1.2 Paizo Inc., et al. “Chapter 2: Fiendish Realms” in Book of the Damned, 141. Paizo Inc., 2017