Moonfang Shroud
Source: World Event. Looks identical to , but pure white. It has an endless duration and a mere 10sec cooldown so you can keep the mask on indefinitely if you want.
The 
Moonfang Shroud is a toy dropped by Moonfang on Darkmoon Island, available only during the Darkmoon Faire.
Guide awaiting review
Wait for Darkmoon Faire
The Moonfang Shroud can only be obtained and used during the Darkmoon Faire event. The item disappears after the Faire ends, so be sure to farm it while the event is active.
Defeat Moonfang on Darkmoon Island
Travel to Darkmoon Island and defeat Moonfang, the wolf boss. She has a chance to drop the Moonfang Shroud, along with other loot such as 
Moon Moon, 
Moonfang's Paw, and 
Moonfang's Pelt.
Note the Bind on Use status
The Moonfang Shroud is Bind on Use, meaning you can sell it on the Auction House or trade it to other players. However, it is unique, so you can only carry one copy in your bags at a time — if you already have one equipped or in your bags, you cannot pick up another.
Tips
The Moonfang Shroud has a 10-second cooldown and an endless duration, so you can keep the wolf mask appearance active indefinitely by reusing it before it expires.
Using the Moonfang Shroud does not trigger a global cooldown, allowing you to macro it alongside your other abilities with /use Moonfang Shroud for the wolf howl sound effect.
