He illustrated Shallan's sketches in The Way of Kings, Words of Radiance, and Oathbringer, plus the centerpiece of Szeth's chapter icon, and he created concept art which ultimately led to the move of the Shattered Plains from Yolen to Roshar. He also did the illustrations for various stories within Arcanum Unbounded.
He can be found on DeviantArt here.
There is a YouTube interview with Ben McSweeney here.
- Basically, Inkthinker is responsible for the Shattered Plains ... being moved to the new book.