A homebrewed game of Dungeons & Dragons 5th Edition
Leading a game of Dungeons and Dragons (or perhaps any tabletop roleplay game) is the perfect tool for an artist with no outlet. It helps train improvisational skills, variegated character creation and most importantly you are free to experiment.
Through working on my own campaign, I am able to practice illustration through battle-maps and character tokens. I can get in the habit of quickly forming and trying out ideas, game mechanics or new rules and receive instant feedback on their effectiveness by gauging the real-time reactions of the players.