To celebrate the launch of Magic: The Gathering - Duels of the Planeswalkers 2012's new downloadable content expansion, imaginatively dubbed 'Expansion,' Steam's running a 50% discount which sees the base game down to only $4.99.

The Expansion brings the option to play as the Archenemy in the challenge mode, in both single-player and multiplayer. It also adds three new playable decks, eleven new Archenemy singler-player levels, six new SP campaign levels, six "sneak-preview" cards from the cardboard game's upcoming expansion 'Innistrad,' four new card unlocks for all decks, and more.

Priced at $5, it's available nnow from SteamXbox Live Marketplace and PlayStation Network.

If you've yet to pick up Duels of the Planeswalkers 2012, Steam's offering it for $4.99 until 4pm Pacific on Thursday. The Special Edition is 50% off, down to $9.99. For those who love instant gratification and shiny things, the sale also extends to all the instant unlock and foil deck conversion DLC packs, making them 49¢ a pop. Or, there's a bundle with all the DLC and the Expansion for $17.99.