All right, I'm pretty sure that there's a component that crazy Barilzar wants in the locked Dwarven chest in the center of Arkngthunch's final chamber. The active furnace vents are a problem, though. Every time I try to get close to the chest, the fire burns and keeps me back. Looks like I need to figure out how to close the furnace release vents. Now if those damn constructs and the damn ghosts will leave me alone for a few moments, I should be able to work this out.