Stone Key.
Legend has it that it's used to open the portal between the Earth Element Plane and the Vorn World.
In the Amber Sword, its other purpose is to serve as a tool for establishing cities in the wilderness. This item and the Torch are twins, with the Torch representing the rules of Order, and the Stone Key being the foundation built upon the elements.
This was a law established by Lord Martha at the dawn of the World, using laws to constrain magic power and elements to construct the World.
This item is immensely valuable in the game, and it's even more rare, as it is seldom traded. It is essential for most advanced quests related to the domain of Earth.
For instance, in Brand's hand, it is the key item for the upgrade quest of Earth Sword Halangea. When the young man saw the shield-shaped stone in the box, his eyelid couldn't help but twitch, and a single voice echoed repeatedly in his mind:
Search high and low with no success, find it without any effort.
