This is a pretty solid build. You have a good removal suite and lots of quality vampires, so I can only a offer a few minor suggestions.
First off,
Cabal Stronghold is not worth it. Even if you can use it, it only gets black mana, and you're a three color deck. Also, because you're investing 4 mana into it, you need to get at least 4 black mana out, which means 4 basic swamps. The
odds of you having 4 basic swamps and
Cabal Stronghold is 0.9% by turn 10. So in 100 games, this might happen once.
There are some other lands that can be swapped as well. You can ditch
Nomad Outpost for
Exotic Orchard, and the bounce lands (
Boros Garrison,
Orzhov Basilica,
Rakdos Carnarium) for the check lands (
Clifftop Retreat,
Isolated Chapel,
Dragonskull Summit). If you're willing to shell out a little money,
City of Brass,
Forbidden Orchard, and
Mana Confluence would make excellent choices.
Next up, your removal package is almost perfect. You'll probably want
Abrade and
Vindicate to give you just a little more artifact removal. But you'll also want to draw into this removal, so you need a little more card draw.
Reforge the Soul,
Faithless Looting,
Read the Bones, and
Night's Whisper should do the trick.
I know you've spent a lot of time on
Edgar Markov, and it's paying off. This is one of the few times that I've seen an
Edgar Markov deck that has impressed me. Good on you.