Lair Assault

From announcement:

D&D Lair Assault is a new Wizards Play Network in-store program that pits tactically-minded players against a super challenge where the difference between victory and defeat is dependent upon your game knowledge, ability to adapt, and a little bit of luck. You’ll pit your wits against some of the most difficult encounters you’ve ever played. Each challenge is a mega-encounter that plays in just a few hours, but many will need to make more than one run at it in pursuit of victory. D&D Lair Assault challenges are available for a few months, and stores can schedule their sessions at any time during that period.