Green Helper Box summons and dismisses Father Winter's Helper, a small gnome battle pet dressed in festive green garb who follows you around, meaning it is a non-combat pet and will not aid you in battle.
Like all pets for this event, it requires that you use a in order to summon it. Snowballs can only be bought or gathered from the Alterac Mountains during the event or made once a day by engineers throughout the year.
Even if you did not obtain this pet in a present, they can often be found in the Auction House throughout the year at highly inflated prices.
There is also a red variant of this pet summoned from a Red Helper Box.
Patch 1.8.4 (05-Dec-2005): Added.