Ferrug is an iron stronghold situated near the largest of the Lakes of Molten Iron, a series of natural whitehot crucibles filled with molten iron. Ferrug's former demonic lord was slain as she lay senseless while astrally traveling to the Material Plane to corrupt mortal hearts. Since then, Ferrug has hosted countless armies of demons interested in gathering workable iron to build other iron strongholds. Because the demons highly value iron, devil strike forces often attack the Lakes of Molten Iron, so Ferrug currently serves as a command center for a force of demons charged by Demogorgon to protect the lakes.

It swarms with herds of armanites, murders of vrocks, and countless ravenous manes led by a willful marilith named Galizsheth. Across the lake lies Raazorforge.