Shiver

A ritual-enhancing drug, shiver is made by drow and usually reserved for rituals and festivities.

Production

The domestication of dream spiders gave drow many advantages. It gave them a ready supply of meat and silk, and it also provided with painful but elucidatory visions whenever the spiders disagreed with the drow's husbandry decisions.
Over time, the drow learned to harvest their poison and turn it into its concentrated form. To do so, they create watertight sacks with the spider's webbing, add root sap, and let it ferment. Once fermented, the resulting liquid is simmered and the venom added right at the end.
The mixture is then stored in a humid room until crystals start forming on the outside of the sacks. The crystals are removed (and often fed to dream spiders), and the resulting mixture is carefully stored in wax bubbles.

Consumption

Consumption of shiver is restricted, amongst the drow and those they trust (usually other elven people, and in some instances, gripplis) to highly respected people and people in positions of authority. Very rarely it will be provided to specific individuals if divine signs point to their importance in the ritual.
While the substance is highly addictive, its restricted usage for rituals and the societal customs and expectations mean that most drow people never develop an addiction to shiver.
When shiver or its production falls in the wrong hands, however, addiction is fast. Addicts crave the hallucinogenic, vivid dreams, enough to go hunting wild dream spiders or raiding drow tunnels.

Shiver troubles

The PCs killed the Inkmaker, who was secretly producing shiver and distributing it along the gripplis of Pertkwugo.
The high amount of people having highly vivid dreams had already affected the plane of dreams. The sudden stop of dreams brought about a riff in the plane of dreams, which allowed nightmares and other creatures to spill from it.
This, in combination with Bogwaguu's mind-controlled state has driven the city of Pertkwugo off the rails and it is in complete chaos.
When the PCs return, they will find most of their allies dead, hidden, or gone elsewhere.