Dark Fog

An element that is found only in the Palace of Twilight, the eighth in the Legend of Zelda: Twilight Princess. This mysterious haze-like element is comprised of shadow crystals created by Zant's wicked magic. It is scattered across various parts of the Palace, and if Link is to come into contact with the mysterious element, he will transform into his wolf form, and will be unable to transform back into his human shape until he leaves the fog or clears it. Once Link obtains the Light Sword, he will be able to clear away Dark fog.