Blood Dreg is a Consumable Item in Bloodborne.
- Received from killing hunters while in the Vileblood Covenant.
- NPCs will drop these as well but you must have the Corruption rune equipped. (Confirmed on Djura)
- NPCs when killed in other Hunters' Worlds also count.
- There's very low chance that they drop from Hunter NPCs inside Chalice Dungeons - if the Corruption rune's equiped.
- The Mergo's Attendant that drops items every 60 seconds can potentially drop Blood Dregs, although the drop rate isn't very high.
- Used to increase covenant ranking by offering to Queen Annalise
- Using them from inventory will give Insight (+1) without adding rank in the covenant
- The blood dreg item looks suspiciously like sperm cells. Perhaps that is what Annalise, Queen of the Viledbloods needs in order to bear a child.
- Lore theories are discussed under Blood Lore - What might "Darkness" have to do with "Blood"?
- Dark Souls 3 has Human Dregs which explore a similar concept.