Growing up Greg Capullo was my hero, When he began working on spawn he took what was originally a Spiderman and Batman hybrid and turned him into a something closer to Frankenstein or Freddy Krueger.
The Big Picture
The first thing to look at is how the composition has an entirely different second read in its composition. If you take the image and make it black and white and play with the curves a little you get this:
Thumbnail analysis and
Here we have a simplified version of some of the value tones and how they contrast with what is around them on the page. There is almost a rhythm to the number of different tones of value and where they are placed. In order for a illustration to be successful it needs to have the full range of tones that define the foreground, mid ground, and background. Capullo uses multiple forms of overlapping and a rhythm of tones that climb from the bottom left of the page to the middle of the page where Spawn is.
You have the first zombie, that's midtone head is contrasted against the bright light of the moon. Next to him the second zombie is contrasted, both by the midtone tombstone in front of him but also the zombie who is a higher key of white behind him, also notice her hair is yellow. So we are now moving away from the greens in the foreground to the red found on Spawn's cape. It also gives you an idea of where he is placed. We then go back to a midtone with the grave stones that seem to be level with the tree right in front of spawn that cuts into the picture.
We then see spawn, placed in between two points of interest that tell us where he is in the picture. One sits in front of him, the other a fair ways back. We know he is at the top of the hill, but there is still a distance behind him that wraps around to the declining side of the hill. So we climb up the picture with the different "beats" of tones til we get to Spawn, then we climb only a little more before Capullo shows us more depth of the graveyard beyond the hill.
There is a lot of overlap going on here in the illustration and I've numbered them in order as they work their way back into the illustration. Also note that on Number 6 there are two other tombstones at the same level. This could be just to box the eye in and keep the distances uniform across the picture.
Our focus bounces back and forth between the first zombie and Spawn but carries in a circular route from the first zombie, to the second, then the third, then to Spawn, to the moon, and back to the zombie in the front.
I haven't read Spawn in years so I don't remember any of the stories, but I doubt this was about any particular story. It was much more about the concept. Most of Capullo's covers are more conceptual rather than literal. This cover feels reminiscent of earlier issues of Spawn where he goes to his own grave to dig up his body.
We have a lot of different elements used to create a depth of field around Spawn hes blocked in from the negative space created by the moon, his cape, both trees and the landscape beneath him. The line work in the cape could double as arrows all pointing to Spawn. The zombies are like stepping stones to Spawn that create a circular composition.
The colors of the grass, the green fungus on the zombies and the blue tint of the sky are all the same tonal range. Very dull colors that contrast to the bright red of his cape. He also uses yellow in the third zombies hair to help make the transition.
Our foreground is defined by our darkest values, which contrasts to the light of the moon and the variation picks up the most at our focus point: Spawn.
Capullo uses a variation of light to light and dark to light transitions on the cape which gives an abstract look to it but is still recognizable as a fabric.
The linework here is used to create the texture on the faces of the undead. They contrast with the cleaner shapes of their suites and Spawn's cape.
This was mentioned before, I feel like this is intentionally reminiscent of the original books. Spawn is back from the dead, but something is watching his every move.
The linework in the hair and facial details of the zombies is also implied on Spawn's face.
Grass and moss/fungus on zombies. The crater lines emphasized on the moon.
The contrast points between the zombie head and the moon itself. The contrast between, the bright red cape and the muted blues and greens of the zombies and graveyard.