In 2011, Blizzard added some major updates and improvements to the holiday, changing Tricky Treats from edible confection into a form of currency that players can use to buy pets, masks, and wands. This year has some new loot available -- three costumes for your pug pals, and a new costume for players as well, the Exquisite Costume Set: "The Lich King." And for all you pet collectors out there, this year you'll find the usual Creepy Crate, Sinister Squashling and Feline Familiar as well as Widget the Departed and Cursed Birman, two new ghostly kitties to add to your collection. Toy collectors will want to make note of the Little Wickerman and add him to your Toybox if you haven't already.
As with most of our holiday guides, I've arranged the achievements in the rough order they should be completed, noting which achievements are required for the meta and which aren't.