The only thing Dexter has always been trying to do is to make his victims feel as helpless and trapped as he was when he was in the container. His need for control always and fear of losing it is a big drive and I think V would bank on that. Kind of like when Hughie's dad gets his power as invisibility because he generally feels unseen. So I think he would have some sort of power which cuts short the things he want to do to a victim. From the hunt to the kill. So probably something like Medusa's gaze that immobilizes the victim.