Castle of Wizardry by David Eddings
Series: The Belgariad #4
The Orb has been recovered, but that does not mean all is well. The orb must be returned to the Hall of the Rivan King and the Rivan King must be returned as well. The Queen must be presented to the King. The Kings prepare for war, but no amount of battles can decide the outcome. The Rivan King, Belgarion must fight Kal Torak. The adventure drastically changes shape as a small party struggles to meet Kal Torak while the others prepare for war led by the most unlikely of heroines.