Various.

There is a knockout move, so dangerous and deadly, its only spoken of in whispered rumours on the dark web, classed years ago as extremly unethical and so illigal there's no mention of it at all in any law book.

This move is called the Caveman Manuver, there are a cluster of nerves at the base of the neck, that lead to the higher functions of the brain, one manages intellect, the other speech, the other manages walking.

If you were to hit them at just the right angle you would sever the connection between the nerves and the brain, this will revert the brain to nothing more than how it used to be during the Age of the caveman, the subject would be reduced to their most primal version pf themselves, they wouldnt be able to speak, only grunt, and they would want only two things, to find a mate, and to fuck, day in, day out.

Should anyone be subjected to this, it is irreversible, the person they once were would be gone forever, leaving behind a simple primitive with a high sex drive.....