Book Of Thunder

When Score, Helaine, and Pixel rush to the planet Dondar to rescue their unicorn friends, they come to realize something is very wrong with Tychus, the rogue unicorn who has taken charge of the herd from Thunder; as the trio learns more about Tychus with help from their magical guide Oracle, the wizard Shanara and her sleepy red panda named Blink, and a unicorn named Darkstar, they realize his devious scheme will endanger all of Diadem. Reprint.