Valve's at it again, following up their Dota 2 Halloween event which led to the hatching of thousands of Greevils with their winter event Frostivus. Check that, apparently the Greevils weren't notified, because they've ruined Frostivus and instead we'll get The Greeviling. What's The Greeviling, you might ask? It's what happens when you get free things from Valve, that's what it is. Next time you should know better.
"Misery piled on misery! As the cold closed in, how we looked forward to Frostivus. Instead we get The Greeviling! The shops have been plundered, our gifts ripped open, our precious items scattered through the woods by a dire tide of Greevils! What caused this swarming chaos? Who hatched all those Greevil eggs? Who can we blame for burying us in this horde of mischievous imps? What's that you say?"
In the same vein as Diretide, it appears Dota 2 will soon be patched with a winter holiday special event. In The Greeviling you'll likely be clearing up the Greevil infestation -- Valve even recommends bringing your own Greevil who can help you in tough spots. Slaying Greevils may result in a "gift for friend and foe alike" so expect a competitive event, unlike the cooperative Franken-Roshan event from Diretide.
Dota 2's store will also be stocked full of new armor and items, of which Valve certainly recommends you gift to your friends. Greevil eggs will also be available, but only in the store. No more free Greevils, because look how that worked out. Check out the Dota 2 event website with three pages of buildup. Expect the patch to hit sometime soon.