Earth: I wouldn't even need metal or lava bending. Earth benders can bend with just the slightest movements and can bend with their arms tied up. Also I would focus on shifting the ground slightly under opponents to break their stance and make them lose their balance. Air: Ever since the last airbender shows, I always wondered about this possible dark side to air bending. While I have many different issues with the Legend of Korra, I liked how they included the skill of vacuum bending (removing air from an area). How can someone try to bend if you remove the oxygen from their body? Also fire can't burn without air, so fire benders can be rendered useless.