The Serpant addon for Wraith results in invisible wraith able to attack.

captain_murphy

On Badham preschool, the wraith was pallet stunned while visible. Went invisible to loop me around the pallet a bit, then broke the pallet. He stayed invisible, gained a red stain, and was able to attack. He remained invisible while carrying my body and hooking me.

After hooking, he rang his bell to turn "invisible" and remained invisible.

Seems like from a survivor's perspective, Wraith stays invisible while using Serpant. Might not remain invisible from killer's perspective.