These abilities are individual drops, however it is possible to receive multiple abilities in a single kill. When received as a drop it is automatically learned; it does not drop as an item. When learned, the message "You have unlocked the Sacrifice ability!" appears in the chatbox.
Sacrifice initially always did 100% of the weapon damage. This was changed on 17 December2013. The ability now deals damage up to 100%.
When released, the ability did not work with magic weapons. This was fixed on 17 December 2013. It can also be used without a weapon.
When released, it initially did not generate any adrenaline.
The ability only bypasses protection prayers from other players. It will not hit through the prayers of monsters such as Elite black knights.
During the third world event, Tuska Comes, this ability was available for 3,500 Reward Currency.
In PvP Sacrifice will always heal you for 25% of the damage dealt, and when the target dies it will heal you for 100% of the damage dealt on top of that. Essentially healing you 125% of the damage dealt in total. It is unknown if this is a bug or not.
In some cases, Sacrifice does not need to kill the target in order to provide increased healing. If Sacrifice is used to bring Yakamaru's health to 0 at a pool (even if this isn't the final pool), or if Sacrifice is used to bring Araxxor's health to 0 (even if the Araxyte spiders immediately heal him for 5,000 health), Sacrifice will still heal for 100% of damage dealt.