Sunn O))) and Boris are an American drone doom metal band and a Japanese experimental rock/doom metal band, respectively. They collaborated for the recording of Altar which was released on October 31, 2006 through Southern Lord. In addition to Sunn O))) and Boris, the album also boasts an extensive roster of guest musicians and collaborators such as Kim Thayil, Joe Preston, Phil Wandscher and Jesse Sykes (both of Jesse Sykes & The Sweet Hereafter) as well as longtime Sunn O))) collaborators Tos Nieuwenhuizen and Rex Ritter. Altar was released in numerous formats: a normal edition was released October 23, 2006 via Southern Lord, and a numbered edition with a bonus CD was released the following day. This edition features a bonus disc titled SatanOscillateMyMetallicSonatas with a 28-minute track titled "Her Lips Were Wet With Venom," featuring Dylan Carson, Rex Ritter, and Tos Nieuwenhuizen. Japanese label Inoxia Records released their own limited edition 2CD version on November 27, 2006 which features a bonus track on the first disc, "The Sinking Belle (Black Sheep)," and also features "Her Lips Were Wet With Venom" on the second disc. The 3LP release by Southern Lord contains all of the songs from the 2CD edition, additional pictures, and liner notes by Kim Thayll. The Daymare Records 3LP version was released in Japan on March 23, 2007 and features an exclusive bonus track, "The Sinking Belle (White Sheep)." On December 10, 2007, the bands collaborated at the Forum in London along with a number of the guests featured on Altar for a live performance. A 3LP picture disc version of the album, limited to 500 copies, was sold exclusively at the show. The bands have since repeated this collaboration for the first time in the United States at the ATP New York 2010 music festival in Monticello, NY on September 5, 2010 and two days later at the Brooklyn Masonic Temple. Read more on Last.fm.