Magician: Master

The Tsurani, a warlike feudal slave-owning race, use their advanced magical technology to construct a "rift" which allows them to invade the medieval land of Midkemia. Pug, an orphan apprenticed to a magician (a low status profession on Midkemia) is captured and taken back as a slave, but when he is discovered to have powerful magical talents he is trained to become one of the Great Ones, the magicians who are the highest status Tsurani caste, and renamed Milamber. In the process he is introduced to the arcane power struggles of the Tsurani rulers and how they relate to the war on Midkemia, and is enlisted into a plot by one of the Tsurani noble houses to end the war.