Kyralia series

Once a year the magicians of Kyralia sweep the beggars out of the capital, and once a year the beggars throw stones. This time one of the stones goes through a shield that is not supposed to be permeable, and the girl who threw it — Sonea, out of the slums — turns out to have power the Magicians' Guild can neither leave untrained nor comfortably own. Imardin has a hard class line running through it, and the Guild has always sat on the good side of that line without having to think about it. Trudi Canavan wrote two trilogies in this world. The Black Magician Trilogy — The Magicians' Guild, The Novice, The High Lord — is Sonea's education and the secret waiting at the top of the Guild. The Traitor Spy Trilogy picks the story up twenty years on, with her son, a Guild changed by what happened, and a hidden society of women magicians in a neighbouring land who have their own reasons for staying hidden. The pleasure is school-and-society fantasy with class anger running under it: cruel classmates, an apprenticeship that costs, a magic system with real prices, and characters permitted to be wrong for a long time before anyone corrects them. Read the Black Magician trilogy first and in order, beginning with The Magicians' Guild, then the Traitor Spy books.