I'm looking for cultivation novels where MC cultivates a technique that has a single move or a single form, for example a single stab and that's it but it would be very overwhelming and if MC unleashes this attack then the opponent will get 1-shot. For example, MC unsheathes his sword and everyone, if he wills it, will be cut down. Or he throws a single straight punch and the enemy is obliterated. Ideally a technique that is extremely difficult or "impossible" to learn/master but somehow only MC manages to do it. Something like that
MC from unparalleled after ten consecutive draws has an insta kill sword draw that's his best move. He doesn't use it often though since most people aren't worth it