Once a proud race of dwarves, years of slavery to mind flayers chiseled any honor or warmth from them, as the years in the Underdark greyed their skin. They are now a race of slavers, scavenging any material whether organic, mineral, or sentient, from the depths of the Underdark.
Most of them have skin of ashen grey, their hair is usually white, and are almost always bald including females.
After generations of breathing in the air of the Underdark, the Duergar seem to have absorbed some of it's magic allowing them to enlarge themselves into large hulking warriors for a short time, or slip away into the darkness if the need arises.
In the Underdark of Avalorn, they have formed an unusual alliance with the Drow Elves and together they have turned their mutual hatred for those upon the surface into a mission for complete destruction.