Onyx dragon bolts (e) are onyx dragon bolts that are enchanted via the Enchant Crossbow Bolt (Onyx) spell by a player with level 87 Magic. The spell enchants 10 bolts per cast, and uses 1 cosmic, 1 death, and 20 fire runes.
Enchanted onyx dragon bolts have a chance of triggering the Life Leech effect. This will deal 20% extra damage and heal the attacker's Hitpoints by 25% of the total damage dealt. This does not work on the undead, as they have no "life" to leech.
The special effect has a 10% chance of activating in PvP and a 11% of activating in PvM. If the player has completed the Hard Kandarin Diary then these values increase to 11% and 12.1% respectively. The Kandarin Diary boost is always active regardless of whether the headgear is equipped.