He is a Demigod mentioned in _Faiths & Pantheons_ and looks like he will suit my purposes. I wonder why there isn't a (human) god of dreams. FR has a god for everything, how is this common (imho) portfolio missed?
Savras does have an entry in the FRCS Faerunian Pantheon (pgs 234-5), and has a few paragraphs devoted to him in Magic of Faerun (p 6), which includes the passage, "[his worshippers] also study prophecies and interpret dreams..."
During the arcane age (Netheril), Selune was the godess of Dreams, and Shar godess of Nightmare. They have lost some of their power since, especially Selune, and this aspect of their portfolio. But they may try to reclaim it