This item was a reward from the discontinued Squeal of Fortune.
This magic vial can be used instead of a normal Vial of water when making unfinished potions for the Herblore skill. These vials can stack, meaning you can make 27 unfinished potions at once instead of the normal 14.
A forum account is required to apply. Good luck! Be sure to check your forum messages regularly for updates regarding your application!