Rabbit's foot

Summary
Gaius gave Merlin a lucky rabbit foot, an item believed to protect you from evil spirits. Gaius said it was given to as a child but he doesn't believe the superstition. When he tries to retract it, Merlin keeps it and takes it with him to the Isle of the Blessed.

When his mother, Hunith's life is taken in exchange for Arthur's and she falls gravely ill, he gives her the rabbit's foot for luck.

List of appearances
Le Morte d'Arthur