Spawn and Subby are very well done, Clown needs more definition, I could barely tell who he was at first. I'd have either shrunken him or widened the red flame/aura thing a bit perhaps to make more of his hairdo visible. Up close and personal like that Clown doesn't lend himself well to the monochromatic scheme. Scorpions pose is sort of awkward, and I'm not quite sure what you were going for with it, but he's pretty well drawn nonetheless.
As for the original post, the silhouette idea is fine and would look pretty cool if only the background were more detailed. I'm not even sure what I'm looking at there. Appears to be just a bunch of crude shapes and stars against a solid blue mat. The fire is pretty cool. The MK logo and McFarlane's name look pretty good, but I'd have tried to add some sort of shadow or perspective to the letters and such, because they're a bit plain as is. "Spawn", the word, is arguably the worst aspect of this pic. It looks conspicuously freehand and rough edged. Whatever technique you used to incorporate the other words into the picture should have been applied to "Spawn" as well to keep a uniform look.
Both are very creative pieces. Your digital art skills need development, but your hand drawn art is far superior. I'm sure you'll continue to improve as all artists do. You have the creativity, and the ability.