Created by the Daemons of the Marcher Fortress, this mortar is incredibly strong. If even a small portion is used in the construction of a building, it becomes practically immune to the ravages of time, weather, and physical assaults, and can stand for untold centuries. However, the building takes on an unpleasant and unholy appearance—stone turns black and drips with disgusting ichors, lights never seem to provide enough illumination, and strange whisperings can be heard within its walls. Most sane people soon flee such places; although, Mutants, Chaos worshippers, and other vile creatures find them much to their liking. In addition, a building crafted with this mortar becomes conducive to Dark Magic.[1a]
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