Shadow Crystal Fog is a substance from The Legend of Zelda: Twilight Princess. It is a black fog created by Zant, found specifically in the Palace of Twilight in the Twilight Realm. The Shadow Crystal Fog is, as its name implies, made from Shadow Crystals, which transform Link into his wolf form whenever he comes in contact with it. He can only be restored to his Hylian form when he is no longer surrounded by the fog.