The Prince of Tabor by William White
Tabor, one of the greatest powers on earth, was under siege. The king and queen had died, leaving an infant son to be raised in obscurity. Now twenty years later, young Nathaniel could not have known an evil army again marched on a vastly weakened Tabor. The evil mage, Crepitus, sends assassins for Nathaniel to put an end once and for all to the monarchy of Tabor.