So here is the idea!
Keep on dying and drag the enemy down to the bottom with you, then establish a combo and gain advantage to soar so high that the enemy wont be able to reach you.
Use rituals to power out some kind of defense, stall enemy advance by menacing them with big creatures and/or stall him with your expendable ones. Get any of the "creature dies, I profit" engines into play, while searching for coffers and more lands. Use mana boosts to accelerate some bigger spells, and once you have enough power, start to suck the life out of the enemy while trading it for card advantage.
Pawn of Ulamog - helps with more creatures / generates mana
Reassembling skeleton - main combo card, this skeleton will soon bring your enemies to the brink of desperation
Attrition - Sacrifice a creature kill an enemy creature (self explanatory)
Blood artist, Grave pact, Reaper from abyss, Harvester of Souls, Massacre Wurm - Nice combo cards for the general idea of dying.
Venser's Journal and Necropotence are a nice combo in any mono black deck. To help out the card advantage I included some Promise of Power as well (I managed to put a 33/33 demon into play with this nasty piece of dark magic)
Zenith is for board control, it goes to the library so its easy to tutor him again if necessary.
Leechridden Swamps are just awesome, a nonbasic land that counts as a basic one and bites all the opponents for 1 life is an excellent way of putting that extra hurt on the enemy while you wait for better uses of mana.
Army of the Damned is added just for the sheer joy of destroying the enemy with a horde of tokens that can be sacrificed...and it has flahsback!
Temporal extortion is just awesome! I've seen more wrong decisions on this spell than correct ones. The trick is to know when to play it. The extra turn or half of enemy life can win games easily.
I believe that Liliana of dark realms will synergize with this deck nicely. Mostly because you'll become so strong thanks to cabal coffers, and she can fuel your need for more lands/filter the deck.
Any feedback/suggestion is very welcome!