Cliff-Marble was a building material taken from the Cliff-Quarries of the Edgelands which was used to decorate buildings in the early days of Sanctaphrax. It was prized for its texture and its luminous glow. The Academy of Wind, intent upon outdoing the other schools, managed to secure a monopoly on Cliff-Marble by organizing what was to become the first of the Leagues of Undertown. It then proceeded to cover the entire surface of its institution with Cliff-Marble, transforming it into the most glamorous facility in Sanctaphrax.
Soon, however, the academics discovered that the excessive use of Cliff-Marble came at a heavy price. The material began to attract Glisters, which appeared in droves wherever the material was used and manipulated the emotions of the academics. The Glister infestation grew so severe in the Academy of Wind that its scholars were driven mad, and slaughtered each other. In a panic, the other schools of Sanctaphrax had all Cliff-Marble removed from their buildings, except for the Knights Academy, which kept part of its outer wall decorated with the material.