In the Pleier’s Tandareis and Flordibel, a castle near Poitou, ruled by an evil giant named Karedoz. It loosely corresponds to the Dolorous Tower of the French Prose Lancelot.
Tandareis, one of Arthur’s knights, had to defeat four giants – Ulian, Margon, Darkion (Durkan), and Karedoz – to conquer it, thereby freeing its prisoners and ending its wicked customs. Tandareis became lord of the castle – and its neighbor, Mermin – and later awarded it to Dulcemar, his father.
Source
Tandareis and Flordibel | Der Pleier, 1240-1270