The Furnace of Rath is a cavernous, molten chamber deep beneath the evincar's Stronghold. The vast room is filled with hundred-foot heating elements that convert solid rock into a molten form for the production of flowstone. At the furnace's core, the temperature steadily rises until the lava is white hot, when it is sucked up into the Stronghold far above. This is the font from which flowstone is formed, the molten birthplace of Rath.
The Furnace of Rath is powered by massive quantities of energy drawn from the dimensional barrier overhead.
Such enormous temperatures have to be vented, however, and even with the colossal ducts spewing heat and ash into the Cinder Marsh, stress fractures still form in the walls of the subterranean complex. These fractures often develop into large passages that can lead up to the massive network of caves surrounding the Stronghold's main chamber.