I took an hour or two and drew some owls while watching the 7th Harry Potter movie. The black (it's actually dark purple) ink is in a Platinum Preppy refillable marker (I SWEAR BY THESE -- you just need the ONE and can keep putting ink in it) (https://www.gouletpens.com/collections/other-writing-instruments/products/platinum-preppy-refillable-marker-black?variant=11884751487019) and the green is in an extra-fine Lamy Al-Star (https://www.gouletpens.com/products/lamy-al-star-fountain-pen-bluegreen?variant=11884855885867).
This started as a pencil drawing (see the 2nd image) that I scanned and put into Photoshop. I tried various filters including: Smudge, Ink Outline, some Splatter, changed the Exposure and added a Sepia Photo Filter. After a couple of hours of playing (I’m not very knowledgeable about digital possibilities and just use trial and error) I ended up with a dramatic image with which I am quite happy. The reference was a magazine advertisement.
Part of a series of black and white drawings on birch plywood. I took some liberties with horns and the look of the face. Don't consider this a realistic bison.