Path of Darkness is one of the 22 pathways of the Beyonders, ruling over night, peace, and concealment. Contrary to its name, it is a path of protectors: darkness here is a shelter from horrors, not their source.
The path begins with the potion of the Sleepless (Sequence 9) and leads to Sequence 0 - Darkness. It belongs to the "Eternal Darkness" group together with the paths of Death and Giant.
This path is controlled by the Church of the Goddess of Eternal Night - and it is with the Sleepless potion that service in the Night Hawks begins, where Klein Moretti's path started.