As the brothers ride on, Merlin appears in disguise and shows them where King Royns is. They kill his attendants, wound him badly, and send him to Arthur. Merlin reveals that the knight who captured Royns was Balyn, and again Arthur repents his hasty judgment of Balyn. Merlin says that Royns' brother Nero will come with a great host tomorrow for vengeance and Arthur prepares. Then, to give Arthur's army a chance, Merlin goes to Nero's ally, King Lot, and holds him with tales of prophecy until it is too late for him to help Nero. Balan and Balyn join Arthur's forces and fight brilliantly. A messenger tells Lot what has happened — Arthur has easily destroyed Nero and his forces and is now in a position to destroy King Lot. Lot is furious at Merlin's trick but will not accept terms from Arthur because of Arthur's seduction of Lot's wife.
As for Merlin, he is grieved that Lot must die, but he has known from the start that in this battle it must either be Lot or King Arthur. Sir Pellanor, the Knight of the Questing Beast, kills Lot, for which deed he will later be killed himself by Lot's son Gawain. Lot's forces flee and Arthur buries Lot, Nero, and the twelve kings who supported them. Merlin adorns the tombs with symbolic figures and tells Arthur more of what is to come.
He warns that he will not remain with Arthur long and that Arthur must guard his magical scabbard carefully, for the woman he trusts most will steal it from him. Arthur gives the scabbard to his sister Morgan le Fay for safekeeping, and she gives it to her lover Accolon. Merlin tells, too, of the battle of Salisbury, against Mordred.
