From publisher blurb:
An adventure for master characters
Members of the Esoteric Order of Kyth need capable individuals to transport a relic sacred to their order, the Puzzle Box of Saint Barbatross, along Umbra’s Path to Oblivion’s Edge, an ancient monastery standing on the edge of reality. The relic plays a key part in completing a decade-long ritual performed to drive back the darkness of the Void from where it intrudes into the mortal world. Adventurers undertaking the expedition face terrible danger as they pick their way across a blighted countryside and contend with the minions of a fragmented demon. If they reach their destination, they have a chance to aid the monks in their efforts to combat the spreading shadow, and if they succeed, they will strike a terrific blow against the doom blighting the world. If they fail, the end of all things will truly begin.
Oblivion’s Edge is an adventure for master characters willing to brave the horrors of a porous and treacherous reality. Although it works well at any point in a group’s master story, it works best as the capstone for your campaign.