This deck snacks on clerics and dines on angels. It takes no prisoners and has no mercy. Destroy, consume, corrupt, impale, eviscerate, crucify, torture, befoul, blaspheme and slay your way to victory by unleashing the demon horde on your opponents. Even more fun in multi-player games where the suffering can be extended.
Big revision recently (as of 10/11/14). I played the deck above last night in a couple of multiplayer games, and it faired quite well. Game one went down to the last turn, either he had to beat me on his turn or I'd beat him on my next turn. He managed to get me, but I still consider it a great test of the deck. In game two, an epic 90 minute game, I prevailed by keeping enough creatures (usually only 1 or 2) on the field with constant sacrificing (from creature abilities)...big enough threats to discourage attackers, but not being able to mount any offense. I lost TONS of life early, but held on, and thanks to 2 and eventually all three Demon's Horns, I was able to grow my life from single digits to 75 before winning. My graveyard had more cards than my library (was down to my last 15 cards or so), but with so many low costing cards and a plethora of ways of returning cards to play or combining attacks with sacrifices...I was able to whittle down my opponents while bringing high-casting cost demon after high-casting cost demon into play. Using fast mana (like Dark Ritual) early can put dangerous things on the field long before they should be allowed, that helps. Additionally, in one turn I was able to destroy all creatures before putting one of the Death Pits into play, then on the next turn, put a 2nd Death Pit into play, from that point on, every creature I had, became a HUGE threat, and my opponents had nothing capable of stopping them. Harvester of Souls was a HUGE part of my success, constantly allowing me to draw cards as my opponents fought each other...one kept bouncing a creature back from the graveyard, just to be killed again, so that creature alone allowed me to drawn 6-8 cards, and thanks to Demonic Taskmaster, I had to continue to sacrifice creatures as well...again, allowing me to draw more cards via Harvester. Then, in an attempt to create a two-front war against our mutual opponent (with a white, life gaining deck...up to 48 life at one point), the player attacked me and I was able to block with my Taskmaster (killing it) which in turn enabled me to start building my demonic horde...of course, by this point, I had more than a dozen land in play. Great game, lots of fun. A K/W life gaining/lifetouch based deck, a G/W token generating horde deck, and my mono-black Demon deck.