Duel Decks are a series of Magic: The Gathering boxed sets, each consisting of a pair of 60-card decks built around a rivalry between two planeswalkers or tribes. Typically, each deck contains a mythic rare, several rares, as well as a number of cards with alternate art. Most cards are reprints of cards from previous sets; however, some duel decks contains six cards from the set (examples include "Izzet vs. Golgari" and "Heroes vs. Monsters").
There have been 13 duel decks released to date, and one more announced:
Duel Decks: Elves vs. Goblins was released on November 16, 2007. It consisted of a green deck where all creatures were elves, and a red deck where all creatures were goblins.
Duel Decks: Jace vs. Chandra was released on November 7, 2008. It consisted of a blue deck built around Jace Beleren and a red deck built around Chandra Nalaar.
Duel Decks: Divine vs. Demonic was released on April 10, 2009. It consisted of a white deck built around angels, and a black deck built around demons.
Duel Decks: Garruk vs. Liliana was released on October 30, 2009. It consisted of a green deck built around Garruk Wildspeaker and a black deck built around Liliana Vess.
Duel Decks: Phyrexia vs. The Coalition was released on March 19, 2010. It consisted of a black deck built around the forces of Phyrexia, and a five-color deck built around the forces of the Coalition.
Duel Decks: Izzet vs. Golgari was released on September 7, 2012. It consisted of a red-blue deck built around Ravnica's Izzet League, and a black-green deck built around Ravnica's Golgari Swarm. Six of the cards in the deck were pre-releases of cards in the Return to Ravnica set.
Duel Decks: Heroes vs. Monsters was released on September 6, 2013. Six of the cards were pre-releases of cards in the Theros set. It consisted of a white-red deck build around humans and auras, and a green-red deck built around large creatures with trample.