Aleph Null Sans

Shorthand: ℵ₀!Sans or ℵ₀Sans 
The symbol his eye makes ∅ = null
I picture an encounter with ℵ₀!Sans to go something like:

You attack Sans. The attack is successful . . . but he has yet to turn to dust. You attack Sans once more only to find it didn't work. The negative number above his head has increased and his bones have become nearly as dark as the void.  He laughs at you. "Surely, you can do better than that, psycho?" He inquires mockingly. Suddenly obsidian bones strike you from your shadow without warning paralyzing you, leaving you at his mercy. ℵ₀!Sans has n∅Ne left. He summons a dark blaster which promptly crushes you in its jowls. 

GAME OVER   

. . . I want to say that this is split personality of regular Sans create during an experiment trying to bring back W.D. Gaster. So in other words he's connected to the void (and the null which is parallel to the void and and anything trapped in it too long ends up erased) allowing him to have negative amounts of HP/hope. The only way to kill him would be to bring his HP to 0 while he's in the void, but doing so would leave whoever killed him trapped in the void themselves since he's the only one who could teleport them out. So either ℵ₀!Sans kills you or you end up trapped in the void. . . unless you can best him without killing him . . .

BUT this is all just head canon AU until I animate (I'm new at animating) Underneath.