Scars of Mirrodin is a Magic: The Gathering

Magic: The Gathering

Magic: The Gathering , also known as Magic, is the first collectible trading card game created by mathematics professor Richard Garfield and introduced in 1993 by Wizards of the Coast. Magic continues to thrive, with approximately twelve million players as of 2011...

expansion that was released on October 1, 2010. It is the first set of the Scars of Mirrodin block. This block will mark the return to the plane of Mirrodin. This plane was last visited in the Mirrodin

Mirrodin

Mirrodin was the 50th Magic: The Gathering set, the 30th expert level set, and the first set in the Mirrodin Block, released in October 2003. It is a 306-card expansion set. It is also the name of the block containing the Mirrodin, Darksteel and Fifth Dawn expansion sets...

 block that concluded in 2004. The interim tagline for the set is "The Corrosion Begins October 1, 2010." The plans for this set were first made public by mananation.com when it was discovered that "Scars of Mirrodin", as well as "Mirrodin Pure" and "New Phyrexia" had been registered as trademarks with the US Patent and Trademark Office by Wizards of the Coast.

As with the original Mirrodin

Mirrodin

Mirrodin was the 50th Magic: The Gathering set, the 30th expert level set, and the first set in the Mirrodin Block, released in October 2003. It is a 306-card expansion set. It is also the name of the block containing the Mirrodin, Darksteel and Fifth Dawn expansion sets...

 block, artifacts make up the overarching theme of Scars of Mirrodin; Nearly half of all cards in the set are artifacts. In his May 24 column, Mark Rosewater confirmed that the "Infect" game mechanic in Scars of Mirrodin would bring poison counters back to Magic.

Mechanics

Below is the list of mechanics used in Scars of Mirrodin:

• Infect - A creature with "Infect" deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters. A player with 10 or more poison counters loses the game.
• Metalcraft - "Metalcraft" rewards a player for having three or more artifacts in play. Creatures with "Metalcraft," for example, tend to increase in power and toughness and/or gain new abilities they otherwise wouldn't have. Some cards with "Metalcraft" are themselves artifacts, meaning only two more artifacts are needed to activate their Metalcraft abilities.
• Proliferate - A new keyword action, "Proliferate" allows players to give additional counters to cards and players who already have them. The player chooses which cards or players will get another counter, though the ability is not targeted.
• Imprint - The only returning keyword from the original Mirrodin
  Mirrodin
  Mirrodin was the 50th Magic: The Gathering set, the 30th expert level set, and the first set in the Mirrodin Block, released in October 2003. It is a 306-card expansion set. It is also the name of the block containing the Mirrodin, Darksteel and Fifth Dawn expansion sets...
  
  block, this keyword allows a player to "imprint" some card on the artifact (removing that card from the game). That artifact's effect depends on the card imprinted (for example you can imprint a creature on to reduce costs of spells that share a card type with that card).