There are many ways to play with this deck. Even if you don't have the perfect hand to start using the revive system, you have the tools to stand long enough until you can start bringign your heavy creatures back from the dead OR, even playing one or both Phyrexian Obliterator's if you are lucky enough. A great consist in you having at least 2 lands, 1 Dark Ritual, 1 Exhume, 1 Buried Alive (Mind Rot is only good if you have some powerful creatures already in hand) and a couple of removals.
Even if you don't have Buried Alive to play with a Dark Ritual or no Exhume, do not worry. Like said before, sooner or later you will be able to make the deck work the way you want it to work and until then you have your black spells to protect and help you.
Now, an example of a good hand would be: 1 Temple, 1 Swamps, 1 Dark Ritual, 1 Mind Rot (or Buried Alive), 1 Exhume, 1 Vorinclex and 1 Nefarox. Now, with a hand like this, even if you start second and with no Buried Alive, you can easily get a strong turn 3. Altough, if you are starting second and fighting a red aggro deck, you should be careful of how you would play with a hand such as this and you draw no mana. The Temple can either be useful or not!
Now, here's where you have to know your deck. In the worst scenario where in your draw you get no mana (it doesn't matter if you get a spell or creature) when starting second against an aggro deck, your first turn must consist in you playing the Temple. Unless Iona is the card you scry, DO NOT send that cad to the bottom. Even if you can't use a Buried Alive, Mind Rot can help you start filling the graveyard so, in your 3rd turn you can cast exhume.
However, if you happen to have 2 lands, 1 Dark Ritual, 1 Exhume, 1 Buried Alive and other 2 creatures or spells when facing an aggro deck and Iona isn't in your hand when you can cast Buried Alive, send her to the graveyard. After all, soon she comes into play you can choose a color and prevent your enemy to cast spells from the chosen color. Facing a mono deck, this pretty much assure your win. As a 7/7, you can easily kill your opponent's creatures before they can do letal to you until you can cast more creatures and start the offensive. But, if facing a two or three color deck, carefull with the color you choose if you are against an aggro. Black should be the priority, followed by white and blue/green (in case it has something to destroy creatures with flying). Most red decks won't have the means to use two Stoke the Flames to finish Iona so you shall be safe.
With a good hand like the one in the example, despite the slow start with the temples do not fear to put it in play if you start first and use the scry to your advantage. Even if you have nothing to help you use the graveyard/battlefield play, use your removals to have some control of the game and prevent the Exhume helping the opponent bring an anoying creature by destroying it with Dark Banishing (if possible, of course).
This deck has many ways to work and you can always use the Praetor's do your advantage, either by using Jin-Gitaxia's abillity to help you get all the things you want in hand while forcing the opponent to play with the top card, getting more extra mana with Vorinclex, weakning the opponent and strenghing your battlefield with Sheoldred or even assuring a strong offensive and defense with Elesh.
Even so, despite all the fun this deck can give you, do not be a fool to think you will always win. You can have great victories with it, indeed. And also suffer great defeats. So, for moments like this, if the perfect hand ever comes to play, USE IT!
The starting perfect hand in this deck would be 2 Swamps, 1 Dark Ritual, 1 Exhume, 1 Buried Alive and 2 low cost removals (1 Doom Blade and 1 Go for the Throat - better not have both of them just in case they are not useful for you). With this hand, it don't matter if you go first or second, altough going first is the best way to assure your overwhelming win. Start by using the Dark Ritual and Buried Alive to send your Demigods of Revenge to the graveyard. In your second turn, Bring one of them back. With his unique abillity you shall have three 5/5 with flying and haste ready to attack your hopeless opponent. Even if you went second and are facing a fast deck and already took some beat, you can always use one of them to defend yourself. After all, not even the perfect combo assure your victory if you are vulnerable to direct damage.
Hope you enjoyed this deck and have LOTS OF FUN with it! ;)
Pssst, and time for me to share a little secret: Do not use this deck if you are not ready to UNLEASH A LIVING HELL and make your foes kneel to the power of Darkness! MWAHAHAHAHAHA
Just joking
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. . . or not . . .