(for Xuldarinar, if it wasn't obvious. Also help I'm becoming addicted to Fallout 4)

Shadepox

Type: Disease, Contact
Save: Fortitude DC 26
Onset: 1d4 days
Damage: 1d4 CON drain/day

Shadepox manifests itself in the form of dark pustules, typically around 2-4 millimeters across and filled with what appears to be shadows, or a swirling and dark cloudy liquid, around an injury delivered by the Shadow. The victim of the disease suffers 1d4 CON drain per day, until they reach 0 constitution. Upon reaching 0 constitution, they die and are turned into a Shadow themselves. If the victim's Hit Dice are greater than 10, they instead become a Greater Shadow.