I recently purchased all five Commander 2013 decks, and have had a lot of fun playing with them as precons. However like any good precon it came time to disassemble them. Unfortunately I recently moved to England (from Seattle) and left most of my collection stateside. As such this list is a preliminary one, being built from a box of Theros and the mentioned Commander decks. It is not optimized by any stretch of the word, rather it is a rough draft to give me something to work with and for people to talk about moving forward.
Blind Obedience, and possibly Crypt Ghast, are some extorters you might want to look at. Blind Obedience slows things down (I play it mostly for the artifact clause), and you can get some silly life gain from it (but it can make you a big target early game). These are easy to find, but a little more expensive since they are in standard.
Personally, I always look at the Beacons and Zeniths for EDH. They recycle themselves, and effectively thin your deck. Beacon of Immortality is silly here, and can also be used for politics (instant speed, use on someone looking at lethal damage); it is also a kill spell with False Cure. Beacon of Tomorrows; extra turns are always nice (although very high cmc). Beacon of Unrest lets you abuse everyone's growing graveyards. Black Sun's Zenith should definitely find a place here. A repeatable board wipe that kills indestructible stuff.
On that note, grab some board wipes that exile stuff. Merciless Eviction is definitely good here, with all the modes. You are going to be a target right out of the gates, so board wipes are nice. There are some useful high cost board wipes that kill everything that isn't yours.