Update 21 October: It seems that the Halloween Tournament will start mid-week, according to a Twitter announcement from Rovio to our favorite on-site sleuthing doctor, @Dr-Omega.
@MightyGreenBird @Doctor_Omega There's a special Halloween tournament starting later this week ;) Hunter gear should be fixed soon!
— Red (@AngryBirds) October 21, 2013
Based on the in-game alert that the current tournament will end in 1 day, we may see the Halloween levels appear on Tuesday. We are trying to determine now what to do about Leaderboards and such.
Update 22 October: Angry Birds Friends v1.3.0 has been released for mobile devices and includes enhanced compatibility with this tournament. Also, the description announces that the tournament will start Wednesday the 23rd.
Lock the doors, board up the windows, and hide grandma in the closet. A second annual Angry Birds Friends Halloween Tournament is coming and it’s bringing the Zombie Pigs back from the undead! Can you help the Angry Birds survive the swinevasion? You’ll be able to try in both Angry Birds Friends on Facebook and in the mobile app.
The tourney will feature one of our favorite features ever in an Angry Birds app: The Zombie Pig! These scary swine come back from the dead, emerging from the Earth to seek revenge on the birds. Remember that you will earn your 5,000 points twice: Once for the green (living) piggy and once for the zombie (undead) piggy.
Rovio is only saying that the tournament is “Coming Soon”, so it should be live either this coming Monday (October 21st) and/or the next week (October 28th). We will also have to wait to see if any other features are added, like an Advent calendar-style release. In the meantime, our tournament walkthroughs can help you through the current week!