Get Archangel out ASAP along with Exquisite Blood, Sanguine Bond, and Chalice of Life.
Use vampires to stack health.
Use Sorin's health set and damage to combo sanguine and exquisite.
Profit from further healing and damage from vampires and other cards, including Elixir of Immortality and Sign in Blood.
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Okay, so that's an overview of a perfect hand and draw. Alright, congrats if you get it.
Now, what if you DON'T get that perfect start?
Get land out when you can, as you should in most situations. Try and get a crypt ghast or two out, so your swamps can be tapped for an extra mana.
Next? Viscopa Guildmage and Blood Artist. Both have good early presence with the 2/2, ability to give lifelink, deal damage based on healing, and damage and healing for a creature dying.
Vampire Nighthawks. These are core units for harrass and damage. Lifelink, flying, AND deathtouch? Solid card.
Vampire Nocturnus... Playing with a black heavy deck, you have great odds to get +2/+1 and flying for your little vampies.
BLOODLINE KEEPER. HE IS A KEEPER. He's a 3/3 with flying, who can tap to summon a 2/2 vampire with flying; once he gets four other vampires on the field, he becomes a 5/5 that STILL taps for 2/2 vampires with flying AND gives +2/+2 to ALL OTHER VAMPIRES. A REALLY good card.
What am I missing? Oh, yeah. Archangel of Thune. 3/4 flying that has lifelink and gives +1/+1 counters EVERY time you are healed. With this deck, that's amazing.
DON'T RELY ON THE INFINITE COMBO FROM SANGUINE BOND/EXQUISITE BLOOD. WAITING WILL KILL YOU, AND THEY PROBABLY HAVE DISENCHANTS.
Sorin Markov! The best form of Sorin. Keeping him alive until you have 8 loyalty will prove worthwhile. Controlling an enemy turn, you can make them cast spells on themselves, all in with their creatures on a losing battle, and even TAP THEIR LAND FOR NO REASON.
Chalice of Life gives one health every turn, and you get 5 free damage at 30 hp. It's helpful.
Elixir of Immortality... You get life, and you can put that massive graveyard you may have obtained BACK INTO YOUR LIBRARY. It's a SOLID CARD. It's a MUST.
Disenchants and clear cards for those pesky enchantments, creatures, and artifacts. NOTE: DOOM BLADE AND VICTIM OF NIGHT ARE USELESS AGAINST BLACK, VAMPIRES, ZOMBIES, AND WEREWOLVES. USE FEAST OF BLOOD OR UNMAKE.
Diabolic Tutor...
http://gyazo.com/e1446b8c5ba5513a216e7694ddfdf6db
No, seriously. This card is great.
Now, before you go 'Y U NO DEMONIC TUTOR'. Legality. This deck isn't legal in standard, but all the others. (Extended if you remove Unmake and Feast of Blood)