http://www.wizards.com/Magic/Magazine/Article.aspx?x=mtg/daily/arcana/1152

The Orzhov Syndicate's underhanded dealings wear down your opponents, whittling away their life totals until you have it all. Cards with the extort mechanic allow you to pay {W/B} whenever you cast a spell to "drain" each opponent for 1 life. Better yet, the ability works in multiples! Get more and more creatures from the "Orzhov Oppression" deck on the battlefield and you can take larger and larger bites out of opposing life totals every time you cast a spell.

For the first few turns of the game, lay the groundwork for massive life total swings later by getting as many creatures with extort onto the battlefield as you can. Don't be afraid to cast creatures as soon as you can instead of waiting a turn hoping to extort. Once you hit the middle of the game, it's time to start extorting! Your opponents may not mind your tariff at first, but as their life totals edge closer to 0, they may quickly find the game slipping away.

You need time to set up your extortion racket, so use your removal spells to fight off creatures that pressure you. Angelic Edict and Murder handles the larger threats, while Blood Reckoning makes attacking you a dicey and dangerous proposition.

If you want to add a big finisher to this deck, consider Sublime Archangel from the Magic 2013 core set. This deadly Angel can fly over opposing defenses to deal massive damage. Another card to find is Obzedat, Ghost Council from the Gatecrash set. The guildmaster of the Orzhov, Obzedat is well-versed in taking an opponent's life and putting it to better use.