Castronomancy is a form of Hydromancy involving looking into images on the surface of water in a glass or magical receptacle. If spring water is used in this method of divination, or if the diviner uses a sacred pool or spring, then it is termed Pegomancy.Some diviners prefer to color their water with black ink in order to give a more reflective surface. Often a distinctive receptacle is chosen for the darkened water, on the grounds that the more they like the objects used, more accurate their divination will be.