A non-canon fan supplement for Werewolf: The Apocalypse that presents a new form of Garou martial arts (comparable to the Stargazers' Kailindo) based on channelling Gnosis. Included are six combat manoeuvres, two Gifts, and details of the spirit called Windtooth.
From the Introduction:
Mortla is a series of techniques that employ a rapid succession of calculated strikes delivered to the opponent's body; resulting in various effects ranging from maiming to fatal. The art itself is based on the concept of using Gnosis to augment attacks, enhancing a Garou's natural weapons with the damaging effects of long-term exposure to cold weather.
With Gnosis behind each attack, natural weapons become capable of dealing damage that typically manifests as frostbite. After being hit it's possible for an enemy to experience extreme fatigue, degenerative muscle symptoms, tissue destruction, and a whole host of life threatening conditions. The use of Gnosis makes the cutting nature of each technique possible, making them seem more like something of a minor charm; this reflects the harsh and cold nature of Great Wendigo.