The Cuarto Llave is Spanish for "Fourth Key". It is in the form of a torn piece of sailcloth. The item was originally used by the Benevolent Lodge of Mystery, a mystery solving group in the 1800s.
Scooby-Doo! Mystery Incoporated
It was vitally important for blocking a wind trap, which was sucking everything and everyone toward a small hole in the door to the Air Dimension. It crippled several Kriegstaffebots, and was about to pull Daphne in, but Fred Jones, Jr. got ahead of her with the Carto Llave.
- Scooby-Doo! Mystery Incorporated
- Like the other keys, the frozen scene associates it with a Greek element, in this case air.