Theory: A killer who uses ____ to traumatise sidney

With the announcement of scott foley and mathew lillard, it looked like they were going with a stu's cult thing, but we know he(Roman) was shot in the head. So a lot of you have been theorising about a killer who uses ai masks, and it fits. I would like to add some details to it.

And someone made a post about emma roberts too, liking some posts etc so I wouldn't be surprised if the killer uses her face too.

However, for stu i think he is still alive and is leading a cult of killers. Each killer wears an ai mask underneath the ghostface mask of different characters like jill, Roman, Maybe more to join the list? Stu himself wears his own mask to cover up the fact that he's alive.