Ghostweed is a pale grass that grows in the remote swamps and bogs of the Empire. When dried and smoked, the weed imparts a euphoric experience.
This experience is not without its hazards. The euphoria experienced is the result of ghostweed loosening the imbiber’s soul from their body. Those who have heavily smoked have been known to be able to project their spirits out of their body, with the numerous dangers that come from that adventure.
The Empire has outlawed ghostweed, because it can also be distilled into a thick resin that acts as poison. The poison has the same effect as the smoke, but is much stronger, and therefore is usually fatal. The poison is actually more effective on corporeal undead creatures, who are normally immune to toxins. These undead already have a tenuous hold on their souls, so the this poison is especially harmful to them.