Most movie posters are boring as hell. It's always some Photoshop of the stars, and maybe an explosion thrown in if it's an action movie.
Or at least, that's the way they are in America. Go to Eastern Europe, or Japan, and you'll find posters that have absolutely nothing to do with the film, and everything to do with melting a hole in your brain.
"I've got an idea for a poster. It'll convey that the movie is so awesome, your skin will melt off!"
"Great. So there'll be, like, a skull there?"
"And you have seen a skull before, right?"
"Eh, I can pretty much guess what one looks like."