Snowball fights and tournaments will be making a comeback, as will the repeatable quests in the Secret Lair of the Snowmen. These activities will all be available until 3:00 p.m. EST on January 2nd. The finale event will run in Lion's Arch and Kamadan every three hours from 3:01 a.m. EST on January 1st until 3:01 a.m. EST on January 2nd.
According to the official website, two brand-new costumes, representing Lyssa and Kormir, will be available. We're betting that's a clerical error, since you can go to the game's store and buy Lyssa and Kormir costumes right now.