FTP, name this character in the Ulster cycle whose incredible beauty brought many sorrows.
She lived for a time in Alba with her companions, whose chanting caused every beast and cow within earshot to give two-thirds more milk.  A man sent to protect her and her three companions was forced by an oath to attend several ale feasts, and a man sent to spy on her lost an eye to a thrown fidchell piece.  The sight of a raven sipping blood in the snow prefigured her affair with a son of Usnach [OOS-nach].  Fergus took up service with Ailill [AL-il] and Medb [MAYV] after Eogan treacherously killed her lover Noisiu [NOY-shu].  FTP, name this character in the Ulster cycle whose incredible beauty brought many sorrows.
She lived for a time in Alba with her companions, whose chanting caused every beast and cow within earshot to give two-thirds more milk.  
Deirdre or Derdriu of the Sorrows