This table can be used to generate a prophetic vision, either as a series of images, or combined to a single imprint. What does the vision mean? Unclear, ask again later.
Each row has a positive, neutral, and a negative option. For some rows, the options are related, for example three different materials or three different animals.
For a simple vision, such as one given by the Augury spell, roll a d20 and describe whichever option best suits the question.
For a more complex omen, roll several d20s and choose words for each of them, combining them into a single vision. Visions often have contradictive elements and should not make complete sense. For example, if you roll 8, 15, and 17, and you want to convey something slightly positive, it could become "A bird of prey (neutral 17) in a golden (positive 8) cage atop a tower (neutral 15)". The same numbers for a very negative omen could become "A snake (negative 17) gliding through the steel (negative 8) bars of a prison (negative 15) door."
Of course, you do not have to use these words verbatim. The snake (negative 17) could become a sea monster, a bottle of poison, or a traitor, as the message requires.