When the art description was sent out to artist Marco Nelor, it still had the playtest name "Scab Clan Goblin." Here's the art description that Marco was given to work from:
Color: Red creature (Gruul guild)
Location: Gruul encampment within ruined buildings.
Action: Show a fierce Gruul goblin who is covered in Gruul tattoos. He is holding a spear whose point is made from a scavenged Boros helm and his armor is a mixture of bones and hides. Maybe his lean-to is made from scavenged bits of armor with any guild symbols painted over with the Gruul symbol.
Focus: The fierce goblin warrior
Mood: He might be small but he's not afraid to fight you to the death.
Notes: The Gruul make their camps within ruined buildings.
Normally, an artist will work out a sketch and send it in to the Creative Team to see what they think. Sometimes, they'll provide a few options. This time, Marco Nelor took a picture of his sketchbook with four (or five) options, along with convenient notes!
Because the notations are particularly interesting, we've blown the image up a little larger. This was done after the fact, so please forgive any blurriness.
The team decided it liked C the best, especially with that note about the painted-on Gruul symbol. And here's the final version!