At first glance this may look like a vampire deck, but it's really a deck built around the sacrifice mechanism.
The backbone of the deck is Bloodthrone Vampire and Mortician Beetle, which are pumped (Bloodthrone Vampire temporarily, Mortician Beetle permanently) by sacrifices, and Blade of the Bloodchief, which grows your creatures (doubly so if the equipped creature's a Vampire) when a creature hits the graveyard, which happens frequently when you're playing this deck (and when you're playing multiplayer in general).
Gatekeeper of Malakir makes your opponent sac creatures, feeding your Mortician Beetle and Blade of the Bloodchief, and also grows huge quickly with Blade of the Bloodchief equipped. Bloodghast can hit your opponent if he/she is blockerless, and can also be renewable fodder for your sac effects. Viscera Seer gives you a bit of scry advantage, which is lacking in black, and pumps your creatures that are equipped with Blade of the Bloodchief as well as your Mortician Beetle.
Awakening Zone creates tokens that both are mana sources and feed your sac effects, and that are also chump blockers, with an added bonus: Every time you chump block, you feed your Blade of the Bloodchief-equipped creatures. Consuming Vapors is the most expensive spell in the deck, and it's a great way to get rid of two creatures your opponent controls even if they have shroud. Plus, it's also life gain, and if you really need life gain to stall a couple turns while you have time to whack your opponent down to 0, you can target yourself on the rebound and target one of your large creatures (maybe your Blade of the Bloodchief-pumped Bloodghast, since you can bring it back the next turn with a land drop and start pumping it again) to gain a large chunk of life.
If any of your non-Bloodghast creatures are killed, you can always bounce them from your graveyard with Grim Discovery, which also allows you to return a Verdant Catacombs for mana-fixing.
With regard to land, aside from Swamps and Forests, the deck runs four Khalni Garden, which create tokens to feed sac effects or to chump block if necessary, and four Verdant Catacombs to mana-fix and to bring back your Bloodghast at instant speed. A cool combo is, before your land drop, to sac your Bloodghast to your Blade of the Bloodchief-equipped Bloodthrone Vampire, drop your Verdant Catacombs, sac your Bloodghast again to Bloodthrone Vampire, sac your Verdant Catacombs and bring in a Forest or Swamp, and sac your Bloodghast again. Then attack... your 1/1 Bloodthrone Vampire is now a 13/13 protected by that Vines of the Vastwood you happen to have in your hand. Next turn, it's still a 7/7!
Two cards that every green deck I've ever created include are Vines of the Vastwood and Explore, which I absolutely adore. Explore is land advantage early game, plus replacing itself, and straight card draw late game, which is always good. And the card that is the sixty-first card in every sixty-card deck I create: Kozilek, Butcher of Truth. Either it gets milled and you get to laugh maniacally at your opponent's chagrin, or you draw it--and you can play it pretty quickly in this deck, especially if you have an Awakening Zone or two in play.
The deck only runs 23 lands, but the mana curve stops at 3 (CMC) on creatures, 3 on enchantments, and 4 on sorceries (I don't count Kozilek, Butcher of Truth, since it's really in there to millproof the deck; actually casting it is icing on the cake).
The sideboard runs 3 each of Bojuka Bog, Doom Blade, Naturalize, Tectonic Edge, and Vampire Hexmage to deal with, respectively, decks that play graveyard effects, large nonblack creatures, artifacts/enchantments, nonbasic lands, and planeswalkers.
What I love most about this deck is the synergy. Everything works together. There's no one win condition; the entire deck is a win condition. You're not sitting there waiting for that one card or combo; you can work with whatever you get. Plus, the mileage that you get out of these low-casting-cost cards can carry you pretty far pretty quickly. They get out early, start little, and get huge quick.
