Vale of Shadows

From PathfinderWiki

The Vale of Shadows is a dangerous valley located in the Five Kings Mountains, in which one of Zon-Kuthon's Star Towers may be found. Here the planar fabric between the Shadow Plane and Golarion is weak and the Vale all but appears to be within the Shadow Plane itself; creatures and monsters from that plane may be found within.[1] The elves of Elistia forbid entrance to the Vale of Shadows believing nothing good comes from it and having experienced that few return alive from inside.[2]