I LOVE the idea of this. My first thought would be to do it in a landscape orientation instead of portrait with the things hidden in the dark on both sides. For me, the skull and spider seem like they are on the same plain.....maybe change sizes or try to make one look like it's more in the shadows than the other. Just throwing out some thoughts. Definately keep going with this. Fantastic idea. :)

~Damia~ LeviathanPhotography