This is a new daily added this Winter Veil which has combined two of the old staples, rescuing Metzen the Reindeer and killing off the Greench so you can return the presents he stole.
Instead of having to go to both Hillsbrad (for the Greench) and either Tanaris or the Searing Gorge (to rescue the Reindeer), now everything is handily in one location, Hillsbrad.
It doesn’t matter who attacks him first because once he’s dead, the Reindeer handlers run off and the sacks of presents around the cave become clickable and you can just loot one. On my second character of the day, the Greench was already dead when I arrived but I could still loot a stolen present and Metzen the Reindeer was just hanging around waiting to be reassured he was safe.
I imagine on a PvP server this could be a fun daily.
As a reward, you have a chance to get the new holiday mini-pet Lumpy, the Lump of Coal.
In my second bag, I got a tiny green ragdoll. So I would go as far as to speculate that there is a chance to get a variety of mini-pets/toy related items from this daily.
Happy Winter Veil.