A Lamentation of Thieves
Nullium is one of the building blocks of creation. Known for its magic absorbent properties it is an extremely rare material to find.
The only piece known is a large spherical portion of large rock that resides within the Darkstar Inn.
Many mages came far and wide to examine the large rock not fulling understanding its potential. Any attempt to scry or divine its purpose were rebutted by the rock. One (scrupulous) mage even tried to teleport the rock out of the Inn for his own own purposes but he was also thwarted by the rock’s absorbent properties.
It was original discovered and brought to this place by the Archmage Ezraban (Who lived in the tower that was built before the inn, who performed many experiments on the substance and constructed a machine that he was able to use (with the material as a catalyst) to amplify his light spells.