I have absolutely no idea what to do. Am I missing some instructions somewhere? Clearly lots of people do understand the gameplay from the comments below, but I'd appreciate a bit of guidance beyond what the skull says so I can play.
I see there is an arrow pointing at the silver box, so I stood on the box and nothing happened. I tried chanting and a yellow box appeared, but it doesn't seem to be usable, just shoots across the screen and if I try to create another one the first disappears.