These are not competitions but are ways to push your artistic skills by taking on projects that mimic the parameters of a professional commission. They are designed by Clint and Diana, and cover an array of subjects with all skill levels being accepted (unless otherwise noted).
To participate in a challenge and receive feedback during a livestream you'll need to purchase a "ticket" from the store. Twelve tickets are available for each challenge. The tickets come with the outline of the challenge topic, inspiration images, and a document with links where your image should be uploaded. Tickets usually go on sale the Sunday after the finals livestream (which is every 4 weeks). Participants have 2 weeks to create the concept image for review then have 2 more weeks to finish the image for final review.
Anyone is welcomed to create an image for the challenge and share it in the Discord forum but only those that purchase a ticket will receive feedback from Clint during the livestream.
Many participants make use of the Art Challenge rooms in the Swatches Discord to receive feedback from the community. You can find the Discord server here, https://discord.gg/KsVYfge
You can watch the previous challenge livestream reviews on the channel here.