Complex sentence: Roberta is a blue Acara and niece of King Hagan of Brightvale, being groomed into a diplomat but she is secretly training to be a sorceress under the tutelage of her mentor Seradar.
Split into simpler sentences: Roberta is a blue Acara and niece of King Hagan of Brightvale. She is being groomed into a diplomat but she is secretly training to be a sorceress under the tutelage of her mentor Seradar.