A harmless malady contracted by users of Arcane Magic. Typically prolonged use of magic leaves residue that can accumulate on the body, usually the hands. The residue shares similar traits with the most commonly used spells in a spellcaster's arsenal -- mud for earthen magic for example.
The residue can be easily removed by scrubbing it with a rough cloth, or simply enough, soap and water. But since the busier mages tend to accumulate this residue all too often, many simply do not find the time to clean themselves off and some are left with marks on their bodies that mirror their art.