Whoa, an all-day festival inside KeyArena? It's going to be ripe in there by the end of the day. But, the good news is that the lineup is worth it, "Deck the Hall Ball 2012 featuring The Killers, M83, Metric, The Lumineers, Passion Pit, AWOLNation, Grouplove, Of Monsters and Men and The Joy Formidable coming to KeyArena at Seattle Center on December 4, 2012."