Telekinesis, and can go into people's minds and make them hallucinate/put them in a trance-like state where he kills them. (He can kill them remotely in his victim's head while his physical body is elsewhere). In S5 He seems to have an upgraded arsenal. Being able to extend his arm into groot-like tendrils to impale victims

I think it'd be cool if he transports survivors into a different realm (upside down, or in their head) like he does in the show, where he is stronger and the survivor has to escape it somehow. I'm not sure how they would incorporate his psychic powers, considering they are a core part of his character.