Duel Decks: Heroes vs. Monsters is the 12th set in the Duel Decks series. It was released on September 6, 2013, with an MSRP is US$19.99.
Heroes vs. Monsters contains two preconstructed theme decks, one centered around the heroes of the worlds of the multiverse (white/red) and the other around the terrifying monsters that lurk along the planes (red/green). It is tied to the themes of the fall set Theros.
Heroes vs. Monsters contained six preview cards from Theros, making the product the very first chance to play with the set's new cards. One of these cards in the Monsters deck is Polukranos, World Eater, a legendary Hydra. The Heroes deck features Sun Titan with a new "Theros-friendly" image. There were six new arts in total and three arts that had never been seen in paper before.