Here is a Spider-Man cover I did for Marvel back in 1997. This is the preproduction artwork before it is sent to the graphic designers who add the title at the top, text information and comic lettering. You will also notice the original official Marvel paper the artist used to draw on along with registration marks and technical specifications around and below the image.
Im not sure which version of the Spiderman comic this was (there were quite a few) It says at bottom PP/Spider-man Issue 91. Pencils by the great John Romita Jr.
The abstract formless areas such as the green portion on the upper right in pages and panels were fun little oases where I was free to play with shapes, styles and special affects which later evolved into my abstract work.