The Magic of Oz (Oz Series, Book 13)

The Magic of Oz is the thirteenth book in the Oz series written by L. Frank Baum. Published on June 7, 1919, one month after the author's death, The Magic of Oz relates the unsuccessful attempt of the Munchkin boy Kiki Aru and former Nome King Ruggedo to conquer Oz.
At the top of Mount Munch lives a group of people known as the Hyups. One of their numbers, a Munchkin named Bini Aru, discovered a method of transforming people and objects by merely saying the word 'Pyrzqxgl'. After Princess Ozma decreed that no one could practice magic in Oz except for Glinda the Good Witch and the Wizard of Oz, Bini wrote down the directions for pronouncing 'Pyrzqxgl' and hid them in his magical laboratory.