Where do you use the lucky coin in Avatar Last Air Bender video game?

You're likely thinking of the "Lucky Charm" item in the Avatar: The Last Airbender video game.

There's no specific "lucky coin" in the game. However, the "Lucky Charm" item can be found in the game and provides a temporary boost to your health and energy. It's not a game-breaking item but can be useful in tough battles.

If you're looking for a specific location to find the Lucky Charm, you'll need to be more specific about which version of the game you're referring to (Wii, Game Boy Advance, etc.).