Lost Mine of Phandelver
Yan-C-Bin, Prince of Evil Air, commonly appears to his followers as a tall, thin, elderly humanoid with long hair flowing in the wind. His true form is akin to a tornado.
Yan-C-Bin is a being of great wisdom and pure malice. His plans began at the forging of the world. The most subtle of the Princes, he operates unseen and studies his foes from afar, attacking swiftly and vanishing before they could strike back.