King Uther promised Merlin he would give him his firstborn child in exchange for receiving the powerful sword Excalibur. Merlin took Uther's son Arthur. Years later, Arthur was able to pull Excalibur from the stone where Merlin had left it, proving he was the true king of England. However, a love triangle formed between Arthur, his queen Guinevere, and his knight Lancelot, sowing discord in the kingdom. In the final battle, Arthur was fatally wounded while defeating his illegitimate son Mordred, who he had with his half-sister Morgana. With his dying breaths, Arthur instructed Lancelot to return Excalibur to the lake, hoping it