Cryptomancy

Cryptomancy is a method of divination by unrevealed means.

From ancient Greek kryptos secret, hidden.

See Also:

You may be also interested in :

Divination for Beginners: Reading the Past, Present & Future -Scott Cunningham
The Divination Handbook: The Modern Seer's Guide to Using Tarot, Crystals, Palmistry and More - Liz Dean
The Beginner’s Guide to Divination :  Learn the Secrets of Astrology, Numerology, Tarot, and Palm Reading--and Predict Your Future
Ancient Greek Divination - Sarah Iles Johnston
Earth Divination: Earth Magic: Practical Guide to Geomancy - John Michael Greer