Meltmassif was a substance that was the primary component discovered within the subterranean chambers of Cronal's Shadow Base located on Mindor. This material was also located on comets scattered throughout the Outer Rim. Its distinctive electrochemical characteristic allowed it to function as a transmitter of signals. It saw utilization in the development of the Shadow Throne, the Shadow Egg, and the armor worn by the shadow stormtrooper's. The crystals of this substance were forcibly inserted into the minds of unwilling individuals referred to as Pawns, a process that took place at the location known as the Pawning Table. Upon touching an external object, or occasionally a living organism, it had the capability to dissolve.
The meltmassif served as the environment and communication medium for mineral-based, sentient entities called Melters. These beings had the ability to manifest themselves from the very walls that comprised the caverns. The Melters would then seize any organic trespassers and submerge them within the meltmassif. It seemed that the act of immersing a creature in the meltmassif enabled them to draw upon the creature's energy output.
Cronal exerted control over the Melters, and consequently the Meltmassif, through the use of his Sunset Crown. He wielded it as a weapon, utilizing it to generate pit formations that resembled quicksand, with the intention of ensnaring his adversaries and apprehending intruders.
R2-D2 determined that it was saturated with electromagnetic energy.