Black Ichor, a dark and tarry substance, sometimes bubbles up from beneath the ground without warning.
Black Ichor has many remarkable properties.
The chiefest and most wondrous of these is the way in which it mutates inorganic and organic substances it comes into contact with, transforming them into entirely different substances. Even a few drops of Ichor is enough to produce this effect.
In the hands of an amateur, the transformation is random, and it can only effect a small amount of the target substance.
The Imperial Commission, however, has learned how to direct this process and vastly increase its efficiency.
This guided transformation is known as ichorwerk.
Black Ichor has to be carried in specially prepared obsidian flasks. Even these decay and twist over time, rendering the Ichor inside worthless.