Jealous of Balin's success in drawing the sword worn by "Malvis", Lanceor pursued Balin, jousted with him, and was killed. Another source says Arthur sent Lanceor to inflict retribution on Balin for beheading the Lady of the Lake. Balin killed him in joust and his distraught lover, Lione or Colombe, committed suicide in sorrow. King Mark of Cornwall rode by, saw their bodies, had them entomed, and erected a monument to their tragic tale.
Lanceor is mainly memorable for being one of the comparatively few knights with a lady who is named - Colombe - and because their tomb became a kind of landmark when Merlin accurately predicted that Lancelot and Tristram would someday fight each other there.