If we want to put a dent in the productivity of the Dark Iron forces working out of the Slag Pit, we have to hit them where it's going to hurt the most. It's a little known fact but dwarves, particularly of the Dark Iron variety, need rest! Lots of rest! Now I ask you; How can they sleep without pillows? Exactly, adventurer, they can't. This is why you must weasel your way into the Slag Pit and steal their pillows.