Biantai is the name of a highly dangerous spell from the Isles of the Dawn. It requires immense effort to cast, generating semi-sentinent purple tendrils that will horribly mutate anything they touch, unless an almost-equally immense effort is made to overcome them. It was cast twice during the magical duel between the twins Maior and Feior - the first time by Feior, when it was countered by Tiaohe, and the second by Maior, when it drained Feior of his remaning strength.