A young wizard and the son of a prophet. He helped Arusu and her friends enter the Wizard World in order to help Grande obtain the True Magic book from them. At the end, he failed and was thrown in prison. Sigma's father was killed by the Grand Master when he tried to advise him not to use Black Magic because of he prophesized that a savior (Arusu) will come and save the world. Later in the series, it was revealed that Sigma was actually working covertly against Grande in order to help his father's prophecy come true. (Source: Wikipedia)