The Crystal Mountain

Heaven comes to the depths of Hell in this final Empyrean Odyssey adventure starring half-demon Kaanyr Vhok and his succubus lover, Aliisza
 
Having escaped from his gilded cage in Heaven into the claws of demons, the half-fiend ruler Kaanyr Vhok is finally in position to exact revenge on his angel captors.
 
Meanwhile, the succubus Aliisza—an escaped prisoner herself—is unsure where her loyalties truly lie. She has betrayed her lover, her son, and the angel who freed her in order 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. With nowhere else to turn, she must call upon the angels and demons she has just forsaken. Can she convince them to trust her and work together . . . before they kill each other?