The purpose of the Null Sphere is to provide total and ultimate protection to the owner. By default, all interactions with the owner fail. Only permissible actions get through the defense. The assailant merely sees their movement pass through, miss, or is entirely ignored by the holder of the Null Sphere.
It is not possible to forcefully remove the Sphere from its owner. If the holder lets go of the orb, it will vanish and assume a 'hammerspace' state until the owner wishes to physically hold it again. Essentially, the orb is soul-bound.
The only way to remove an orb is for the holder to willingly and deliberately let go and pass it onto someone else. It cannot be pick-pocketed or otherwise taken without consent.
The Null Sphere is crafted through a surge of Eldritch Fury, channeled into a orb the size of a small marble. The orb becomes a piece of void-black glass. It appears faded, slightly transparent and ghostly.