The Cerastes is a serpent of knowledge that lives in the World Tree. They are very rare and catching one is actually considered a good omen, because the bite of this serpent will not kill. Instead, the bite of the Cerastes induces knowledge of the most powerful kind. This piece summons the spirit of a cerastes that will "bite" you spiritually. Basically, what I mean is that this serpent of knowledge will embed seeds of knowledge into your subconscious. These sseds are whatever seeds you want them to be, as you will meditate with this item to tell the serpent what kind of knowledge you desire.