Complex sentence: His mother is King Brandegoris' daughter Claire, who tricked Bors into sleeping with her using a magic ring; this is sometimes said to be the only time Bors broke his vow of chastity.
Split into simpler sentences: His mother is King Brandegoris' daughter Claire, she tricked Bors into sleeping with her with a magic ring. This is sometimes said to be the only time Bors broke his vow of chastity.