Dreamscape — Philip R Benge

Moira Bourbon, the most powerful Satanist ever, had been killed, but instead of suffering the torments of hell, she was taken to the Dreamscape, a hell dimension ruled over by the demon Lord Asbaritch who had decided to make her his consort. From his fortress her powers grew and although she was dead, she wanted two things, to rescue her father from Tartarus, a hell dimension where the inmates were tortured for eternity, and to kill Rob Hinds, but only after he had assisted her attain her first desire.