Its Makengyo Sharingan Anesthesia/Tranquilizer
all you do is use your MS to make the patient unconscious so that you can do surgery or other procedures on the battle field if you need to;
anbu itachi tried to use it on anbu j and he almost killed him.
of course you need to make sure you give the patient a pleasant fantasy and not tourture them.
you want to try it out?