Jones, Diana Wynne. Mixed Magics. Greenwillow Books, 2000. ISBN 0-06-029706-9. $15.89. 138 p. A 5+ FI Reviewed by Janet Francis Chrestomanci, Jones’ all-powerful enchanter, appears in each of her four stories, which all deal with the misuse of magic by characters who may or may not realize that they are being used by the enchanter. Jones said that each time she writes a book she tries to say something new; the stories collected here-”Warlock at the Wheel,” “Stealer of Souls,” “Carol Oneir’s Hundredth Dream,” and “The Sage of Theare”-certainly do not lack new ideas or a deft touch of humor. An evil enchanter doing good things for bad reasons, kidney beans in cans (each bean is really a human soul), and a media-hyped little girl who dreams her fortune-all appear in these relatively brief (and always too short) tales.