The Crystal Mountain — Thomas M. Reid

What could bring heaven to the depths of hell?

Aliisza betrayed her lover, her mentor, and her son in order to try to stop the dark plot to kill the goddess Mystra. She failed. Now the goddess is dead, magic is malfunctioning, and Aliisza and her companions are trapped. Her only hope of escape lies is in convincing the angels and demons she just betrayed to trust her and work together--before they kill each other.