The Bump

A nighttime creature that lives in the attics of homes. It consists only of a bumping head that has no body and travels by 'bumping' its way across a floor. Thus, someone observing an upstairs 'bump' would hear a heart beat like continual noise as if a single footstep repeating. This footstep gains speed as it osilates toward its next host. If the victim does get consumed by a bump, their head is imploded and 'absorbed' by the bump, who is the head of its last victim.

They often appear like those little bobble heads you get from a coin machine at a grocery store that also sells gum.

It must be a home featuring the bond between two people, to show up.

If one becomes the victim of a bump that consumes their head, then your soul in the Material plane goes into the attic they once inhabited, reliving some memory ad infinitum until they find another head to replace. This attic repeats in their heads until the end of time unless another head is consumed.

Attack: The Bump attacks by 'bumping' toward the victim, then envelopes the person with an enlarged mouth of total darkness that becomes the size of the entirety of the victim's peripheral view which to others remains invisible. To onlookers the Bump is merely staring at the victim, as if in frozen time and space. Once the head is consumed which takes 30 seconds to a minute, the new head is of the victim in question, and that person's body disappears.

A saving throw against one's Self Worth is required. Bumps prey on the cowardice of others, and find narcissists, egotists, and people who don't think for themselves, easy victims since deep down these people consider themselves next to worthless. Upon being attacked, only the victim can see inside the Bump's mouth, which is often said to consist of an melting orb of people's lost heads and memories at it center, before one's own head is taken. If the saving throw succeeds, the Bump simply moves on.

It is rumored that good luck follows those who survive a visitation from a Bump. If the saving throw fails, one must bat the thing away with the modifier of one's Self Worth as a negative value to attack each time. i.e. SW is 15 so instead of a +2, it's a -2 to attack in place of the attack modifier. (D&D can use Charisma unless incorporating Self Worth as a new D&D attribute which would then use D&D ability modifiers.)

If other PC's try and kill a Bump to prevent even having to roll a saving throw, they can only reduce the hit points of the Bump to 1, at which point it merely bumps away, but could return in the attic any of those same PCs visit in the future, no matter where they are in the world.