The Cult of the Sanguine Harvest is a document in Pillars of Eternity II: Deadfire.
Excerpted from The Legends of Eora by Amaia, scholar of Rauatai.
"In all my travels among the islands of the Deadfire Archipelago, I have heard tell of no cult so feared as the Sanguine Harvest.
All that is known of them is hearsay and rumor. Based on this, I would be inclined to conclude that the Sanguine Harvest are little more than a story. But how is one to explain the disappearances of innocent kith around the 16th of the month?
What may have befallen these poor souls is dismal indeed. Those few I spoke to who claimed knowledge of the Sanguine Harvest would swear to me only that they received it secondhand, and they had this to say:
On the 16th of every month, the Sanguine Harvest choose one unlucky captive to kneel before their altar and become fodder for a cabal of fampyrs. Through this act, the leader, or 'Grand Harvester,' empowers a fearful, soul-draining greatsword. To what end the Grand Harvester then puts this sword is unknown.
The cult members, or 'Harvest Cantors,' then dance around a fire in a state of mindless, ecstatic joy.
They clothe themselves in robes of black edged in red, and on their robes is the image of a large dagger cutting three kith in half.
It sounds too ridiculous to believe, does it not? And yet, I wonder."
- Arkemyr's Manor: Bedroom, in the bookcase on the wall.