Teysa Karlov embodies the scheming, ruthless side of the Orzhov Syndicate. She shows no mercy, and those that attempt to fight back are crushedand then promptly brought back to fight for Orzhov once more.
The Orzhov picks its opponents part, 1 life at a time. The extort mechanic encourages you to sit back behind your defenses, slowly leeching life out of your opponent until there's nothing left. Creatures like Bane Alley Blackguard prioritize toughness, letting you build your defense early and giving creatures with extort such as Syndicate Enforcer and Basilica Screecher plenty of time to start stealing life from your opponent. Once the game is under control, Teysa, Envoy of Ghosts should be more than enough to finish your opponent off.
One card in this deck that's likely to catch your eye is the "split card" Profit/Loss, which gives you the tools to dramatically affect a combat phase. Do you cast Profit for 1 ManaWhite Mana to give your creatures +1/+1, or do you cast Loss for 2 ManaBlack Mana to give your opponents' creatures -1/-1? Or do you wait until you have five mana and use fuse to cast both halves together? The results will be devastating.
For more cards that are perfect for this deck, turn to the Gatecrash set. The legendary Obzedat, Ghost Council is a 5/5 that can drain your opponent for 2 life every turn, and Treasury Thrull is a 4/4 creature with extort that brings a card back from your graveyard to your hand each time it attacks. Also be sure to check out the Dark Ascension white-black planeswalker card Sorin, Lord of Innistrad.