Bodylink

This spell links the parts of your body so their separation doesn't affect you. You can lose your head or limbs without taking damage, though you must reattach any missing parts before the spell ends or you will take any damage you ignored from the initial cut and possibly die (surely die if your head is not attached). If your detached body part is simply pressed in place (likely requiring an action from you or someone else) it automatically reattaches.

While your parts are detached you still control them normally, and they function at any distance so long as they are not taken to another plane of existence. A detached eye still sees, and a detached head can still eat and speak; however, detached hands, fingers, or arms are not able to perform the somatic components for spells.

If you cast this as an action on your turn you can sever your own body part, assuming you have suitable tools.