L. Frank Baum 
The Magic Of Oz [EPUB ebook] 

The Magic of Oz is L. Frank Baum’s thirteenth Land of Oz novel.
A Munchkin by the name of Bini Aru developed a way to change both individuals and things by simply pronouncing the phrase ‘Pyrzqxgl.’ Bini recorded the pronunciation of ‘Pyrzqxgl’ and concealed it in his magical lab when Princess Ozma ruled that only Glinda the Good Witch and the Wizard of Oz were permitted to use magic in Oz.
One day, as Bini and his wife are visiting a fair, their kid Kiki Aru discovers the instructions and later turns into a hawk. To avoid Glinda’s attention and to gather a conquering army from the country’s wild animal population, they disguise themselves as animals and travel to Oz. Kiki transforms both Ruggedo and himself into Li-Mon-Eags when they first show up in the Forest of Gugu.
The Wizard, whom Kiki changed into a fox, pursues the Li-Mon-Eag and his magic bag all the way into the jungle, where he starts turning monkeys into enormous human troops.
How to handle the wicked wizards who have turned into nuts is decided by Ozma and her allies. Kiki Aru and Ruggedo are forced to drink the Water of Oblivion by the Wizard, which causes them to lose all memory of their previous experiences.