The kamaitachi can use its action to polymorph into a swirl of wintry weather. It can revert back to its true form as a bonus action. Its statistics are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form when it dies. While a wintry swirl, it has a flying speed of 40 feet, immunity to the grappled, petrified, prone, and restrained conditions, and resistance to bludgeoning, piercing, and slashing damage from nonmagical attacks.