Okay - monochromatic! I decided to use an image ref, since I couldn't seem to come up with anything I liked. I chose
Caravaggio's Medusa and, because of the violent nature of this painting, thought that red would work the best. I used my usual 12x16" Arches Oil paper, but squared it off to roughly 12x12. It's an odd circular painting, supposedly the artist's nod to the Greek mythology tale that Perseus, who decapitated this Gorgon turned monster, used a round shield to help do the deed. Caravaggio also used his own face in the original, supposedly to suggest that he was impervious to her gaze that turned mortals to stone. (These Greeks didn't play around.)
I used a dinner plate to get a circle that would fit the paper.
Here's my little girl:
I had a great time with this. Here's the palette, all van Gogh oil pastels (except the B&W ones, used to help modify the values):
That link to the painting shows a version that has cut off the bottom, where the blood is gushing around a couple more snakes. Not the best, but it gives the idea.