This is the art of divination by rainwater.
Omens are drawn in various formations and sizes of rain puddles and bowls of rainwater are gazed into until a vision appears.
Bibliomancy or Stichomancy, is the art of divination by means of opening a book at a random spot and interpreting the first line.
The Christianized version of this is called "lots of the saints". which uses the bible or the Gospels.
"Homeric lots" and "Virgilian lots" are ancient forms of bibliomancy by using the works of Homer and Virgil.