Boon of the Survivor

You become immune to power word kill
Additionally, vorpal effects do not kill you and you can survive without your head.
While your head is separated you body functions on your turn but can not cast spells involving verbal components and is considered blinded. Your head is considered incapacitated while not attached

If you have a severed body part and hold it to the stump, it instantaneously causes the limb to knit to the stump.

You also do not need to breath, drink or eat to survive.