Goro Fujita - 4 Seasons
One of the amazing things Quill supported early on was the directional brush. The way it works is Quill remembers the angle you drew the paint strokes from and slowly fades them away as you turn away from them. This can be used in many ways like reflections in glass. But how about four seasons :D
I did a similar piece long time ago but this one is animated. It's so satisfying to rotate the scene in your hands as the seasons change...