The third book of bestseller Silverberg's widely praised Prestimion Trilogy, also the concluding volume of his Majipoor cycle, abounds in rich description of a vast planet peopled by 15 billion beings of several species and ruled by two human kings. Unfortunately, Silverberg seems so enraptured with Majipoor and the history he's created for it that he languishes lovingly in flashbacks and recapitulations that prevent his slim plot, centered on the transfer of power from Coronal Lord Prestimion to Prince Dekkeret, from getting underway until well into the present novel. Delightful as his many fans may find his excursions into extraterrestrial geography, biology and alien religious cults, their sheer quantity detracts here from the potentially intriguing interplay of character in the context of generational torch-passing, as the fortyish Dekkeret assumes his Coronalhood and the once wily and vigorous Prestimion settles into incipient geezerhood. Minor characters, many familiar from earlier volumes, play their expected supporting roles. The most effectively drawn is the fiery swordsman and High Spokesman, Septach Melayn, but even his self-sacrifice, which saves the world for Dekkeret, is lost amid the pomp and pageantry, the might and majesty of Majipoor, the real protagonist of this lengthy cycle of novels, in which inventive language and vivid alien landscapes reign supreme. (June 12) Forecast: With blurbs from Robert Jordan and Ursula le Guin, Silverberg should once again climb genre bestseller lists with this concluding volume.