Lee Sin is one of the most technical champions in League of Legends. You can play him at a basic level with minimal effort, but his skill ceiling is incredibly high and allows you to perform all sorts of exceptional feats and stylish plays. It used to be considered a prerequisite of the best junglers to have good Lee Sin mechanics.
Enter Gripex, another single-champion-focused player who has dedicated an immense amount of time to Lee Sin. If you'd like to see just what the character can do when pushed to his limit and learn more about the jungling role in the meantime, Gripex is a good player to study. His YouTube channel features a variety of full length games as well as montages, and he streams on Twitch regularly.