Scars of Mirrodin Game Day (October 30-31) features special rules allowing players to align their Standard decks with one of the factions featured in the set. Players that align their decks are eligible to win exclusive preview cards from the February 2011 Magic set, Mirrodin Besieged! This change is part of a marketing campaign that will kick off in September, themed around the factions presented in the Scars of Mirrodin block. For more information on Game Day, check out http://www.magicthegathering.com.
To make Magic Game Day accessible to even more players, Game Day will become a Core-level benefit in the Wizards Play Network (WPN). This change will take effect with Scars of Mirrodin Game Day, which begins scheduling on August 12th, 2010. WPN Core-level locations will be able to schedule one Game Day and Advanced-level locations can schedule two. For details on the WPN and its levels, see http://www.wizards.com/wpn.

WPN Advanced-level locations will also get access to the following new benefits:

An Advanced Support Kit starting with Scars of Mirrodin. These kits are identical to a Gateway Support Kit, but with ten additional exclusive prize cards.
The most active Advanced locations will have the opportunity to run WPN Premium Tournaments. This ongoing benefit recognizes the biggest and best-run tournament circuits that our Advanced locations run, giving them enhanced K-values and calling them out on our online Event Locator!

How is the Scars of Mirrodin Game Day going to work?

Magic Game Days will take advantage of the new settings and mechanics in the latest set. For Scars of Mirrodin Game Day, players can build a Standard deck that affiliates with one of the two factions in Scars of Mirrodin. (While having an affiliated deck is not required for Game Day, it will add a unique and significant element of excitement to the tournament.) The top 2 finishers affiliated with each faction receive a preview card from the February 2011 Magic set, Mirrodin Besieged! This is in addition to any top 8 prize cards they might win for their overall event finish.

What does it mean to "affiliate" your Standard deck?

All cards in Scars of Mirrodin are affiliated with one of the two factions in the set. An affiliated deck must have at least ten main-deck cards from the chosen faction, and none in the main deck or sideboard from the opposing faction. The deck must still be Standard legal.

Для тех, кому лень читать:
- Фракций в сете будет всего две;
- Все карты в сете будут принадлежать какой-то фракции;
- Участие в акции с фракциями - дело добровольное;
- Чтобы ваша колода принадлежала фракции, в мейне должно лежать 10 её карт и ни одной карты фракции вражеской.