Remnants of a primordial civilization that tried to gain power from the Far Realms, derro are ancient dwarves twisted by contact with the far realm. The Hafgar clan is one of the few to no longer reside on the material plane, instead making their homes in a series of small caverns across many planes connected by portals.
The Hafgar clan has a long standing animosity with Benedict Oswyn and lay some claim to his artifacts.
The Hafgar’s favorite strategy for taking new territory is to drop in what can be loosely translated as a Weakener. The Weakener robs those on the plane of their intellect, making it easy to conquer with minimal force.