Snowfang
Sold by Beska Redtusk. A pup of Thrall's frostwolf, Snowsong, besting her in combat has earned you a lifelong companion. Beast type. If you are like me and just collecting pets here is the short version: Level a shammy to level 100.
Snowfang is a non-cageable Shaman-exclusive pet obtained by defeating Snowfang in your Order Hall during the Legion expansion.
Guide awaiting review
Level a Shaman
Level a Shaman to at least level 100, then complete the artifact weapon questline until you have your artifact weapon and are back in the Order Hall with the quest to choose a Broken Isles leveling area.
Navigate to Storm's Eye Overlook
Do not go through the portal to Dalaran — instead, head north within the Shaman Order Hall to Storm's Eye Overlook, where Snowfang waits near Aggra and Snowsong at 35.88, 79.33.
Defeat Snowfang in Battle
Challenge Snowfang to a pet battle at 35.88, 79.33; using a 
Iron Starlette with the rotation Wind-Up, Supercharge, Wind-Up, then Toxic Smoke will end the battle quickly. Snowfang deals Frost Shock and Ice Lance and takes reduced damage, so bring strong attackers.
Tips
Snowfang is not cageable and cannot be traded or purchased from other players, so it must be earned on a Shaman character.
A class trial Shaman can be used to obtain Snowfang — after unlocking the Order Hall by breaking down the rock wall, turn around to find Snowsong near the ledge before starting the fight.
