Test of the Twins (Dragonlance: Legends, #3)

Raistlin casts the magical spell that has cost him so much. For him, the Portal opens… But at the same instant, his twin brother, Caramon operates the magical time-traveling device. The fields of magic shift and collide. Caramon and the kender, Tasslehoff, are flung into an unexpected time and place where they make a horrifying discovery. And Raistlin enters the Abyss, prepared to face his most deadly challenge--- Takhisis, Queen of Darkness.