Snow Walk, a powerful but dangerous rite, is attempted only by individuals whose taint or spiritual sickness cannot be cleansed with a Sweat Lodge. The supplicant goes off alone, without clothing or tools of any kind, into the frozen tundra of the far north (or into a fierce local snowstorm) and must survive there for at least three days. The first day may be trying, but it is on the third that the real test begins. If the rite is successful, Wind-spirits summon harsh gusts, hard hails and piercing ice to attack the Garou. If she survives, she is cleansed of any Wyrm-taint or spirit toxins and may even be freed of Harano.
The supplicant rolls Charisma + Rituals (difficulty 7). If successful, the storm comes. She must then roll Stamina + Survival. Only one success is required to cure Wyrm-taint or spirit toxins, but four are needed to banish Harano. If the roll fails, the Garou is reduced to Crippled and must heal as if she had taken aggravated wounds. In addition, she must roll against the Battle Scar chart.
Source: Wendigo Sourcebook