While escaping from Arthur after her attempt to destroy him and Uriens, Morgan le Fay found Sir Manassen bound and about to be drowned by another knight.

Manassen was of Arthur's court, but he was also the cousin of Sir Accolon, Morgan's recently killed paramour. For Accolon's sake, Morgan freed Manassen, let him drown his enemy, and directed him to tell Arthur how she helped him by turning herself and her knights into the liknesses of boulders, which errand Manassen carried out.