Planar Powers (Planescape: Blood Wars Trilogy, Vol. 3)

Aereas is dead. His daughter is growing up to be a beautiful woman, learning from her unle the business of espionage. Nina is close to dying. Her son is training in music at the shop of Boffo the Gnome. The Blood War itself still rages. Even the heavens shake with its fury, and they may well topple, unless these children of heroes truly bear their parents' blood.