Circle of Heroes (The Familiars #1)

by Adam Jay Epstein & Andrew Jacobson

Aldwyn, a street-smart alley cat, pretended he had telekinetic powers so young wizard Jack would chose him as a familiar. Aldwyn then learned that he and two other familiars—Skylar the blue jay and Gilbert the tree frog—were destined to undertake a perilous quest to defeat Paksahara, an evil hare who’d been familiar to the queen.
 
In Circle of Heroes, the third book of The Familiars series for middle-grade readers, Paksahara and her undead animal army control the Shifting Fortress. Aldwyn and his friends have to recapture it to return magic to the queendom of Vastia.