Castle of Wizardry (Belgariad‪)‬

It all began with the theft of the Orb that protected the West from the evil God Torak. Before that, Garion had been a simple farm boy. Afterward, he discovered he is a sorcerer. Now, at last, the Orb has been regained, and the quest nears it end. Of course, the questors must still escape from a crumbling enemy fortress, flee across a desert filled with Murgo soldiers, and avoid the Grolim Hierarchs seeking to destroy them with dark magic. After that, Garion feels assured, his part would be finished. But the Prophesy still holds several surprises for Garion, and for the Imperial Princess Ce'Nedra.