Ruins of Ironcrag Keep

Publisher's blurb: A red light flickers in the distance towards the end of the winding stone tunnel where a wall has collapsed. The main door has been barred by the fallen debris but the collapsed wall luckily gives access to a ledge and balcony above a lake of molten stone. After turning a corner you find yourself in a large room that has partially collapsed, the floor is lined by large metal grates and below them a stream of magma flows out towards the lake. At the far end of the room there is a still intact crescent basin of sorts, also full of this molten rock.