Mature Black Dragon Sinew is a drop from Onyxia in Onyxia's Lair that is required by the hunter epic quest chain.
As a quest objective
-  A Proper String
- Drop rate is approximately 25%.
- Lootable by anyone, even though it's a quest item.
- Cannot be disenchanted.
- Completing the quest chain requires this item and the heads of four elite demons. This item may be looted before, during, or after the quest to kill the demons.
- This item still drops from the level 80 version of Onyxia.
- This item also drops from every black dragon in the Burning Steppes.