I am fascinated by this Star Wars poster

That’s Luke’s face up there, but he’s dead in-universe. I actually have no idea the extent of Mark Hamill’s role in this movie. Why’s he on the ‘bad’ side of the poster, and why is his hair coming out of Kylo’s mask? Or is that meant to be Kylo’s hair?

This is a very pretty poster but it leaves me with a lot of questions.