The Horn is one of the minor Things of Power for calling and emergencies, to be used only twice. It was a Christmas gift to Will Stanton from Miss Greythorne, a small, gleaming, hunting horn. It is found to be of use at the start and end of Silver on the Tree. Will used it to call the Six, Jane, Barney, Simon, Bran and Merriman. Finally, the sixth is him. The second time that he uses the Horn, he's in the Lost Land, and he used it to stop a mortal wheel.