I reckon the composition needs a little tweaking. Don't think having that skeleton arm at the left being cut off at the border works too well (unless it's like that due to the scanning). It'll look better if you raise the angle of the skeleton arm so the hand is at the top left, it'll provide counterbalance to that vampire robot's raised arm on the right.
Also, if the lightsource is the centre character's halo, you probably ought to raise the contrast a little more.
Other than that, this is a really cool and well-thought out piece. It's creative and the way you handled everything else looks great.
thank you so much. this is a full page from my sketchbook, so i never did draw the elbow for the arm on the left. i began with the elements in the center and worked outwards, hence the poor positioning of the arms. i thought it looked wrong when i was working on it. with high contrast the image looked horrible, maybe i wasn't doing it right, but this is closer to how it looks on paper. thank you for the advise, i really appreciate it.