Cataclysmic monster: Sorrastorm

There's an ancient mask found in the middle of the forest, if anyone could find it, he'll became an old Sorra warrior, like long time ago, but in exchange of his own soul. However, Erinstum starts walking around after the end of Tromakos' invasion, and whitout noticing due to his sandstorm's entire body, he stepped on the mask of Sorra with his storm, and thus make the mask took his own form. Now, there's Sorrastorm.