The Shadow Fey

Once a powerful force in the environs of Zobeck, the Shadow Fey, or Lantawathesti Elves, are a race of Elf who split from the ancient Eldar around seven millennia ago, along with the Silvanesti, or Sun Elves, and long before the emergence of the Kagonesti, or Wild Elves, and the Drow, or Dark Elves.
For aeons the Shadow Fey remained in the Shadowfell, a mysterious place in the Shadowlands upon the Ethereal Plane, thought to border with both the Material Plane and the Feywild, and were content to influence things from afar.
Around four centuries ago the Shadow Elves came to Yore with a Royal Envoy and made a diabolical deal with the then rulers of Zobeck, the Lord and Lady of House Stross. They would gift the mortal nobles with powerful fey magic in return for mortal souls, whose warm blood soothed their icy hearts.
For half a century they preyed upon the good folk of Zobeck, until the Great Revolt that led to the city becoming a powerful independent city state under Rada, the Goddess of Gears. The Shadow Fey retreated, but some say they still plot and crave the souls of mortal men.