Get out black creatues and do heavy damage by turn 7 you should have one. Also, this deck sort of ramps in its devotion and black mana. This is done mainly with Crypt Ghast and Lilliana of the Dark Realms. Late game your devotion hits big with creatures like Abhorrent Overlord and Grey Merchant of Asphodel. Lifebane Zombie provides removal while also upping your devotion with a creature. Whip of Erebos provides life sustain against aggro decks and gives good devotion too.
If you like the idea or test it and find anything to fix just plus 1 and leave a comment below..
Updated the sideboard and description. Need suggestions though as this is still in its prototype stage.
I would consider Nightveil Specter as a source of three devotion, and perhaps an Overgrown Tomb or two for Deathrite Shaman. With all your lifegain (I see 10 cards, potentially 14 if you add the Tombs) I would suggest Thoughtseize in place of Duress. Mutavault could also be nice, though more than two copies is pushing it. Disciple of Phenax can serve as disruption, but Desecration Demon and Crypt Ghast are already good four-drops. Having seen Monoblue Devotion's success, Monoblack Devotion seems like it could be great.
Thanks helloooo for the suggestion but Overgrown Tomb really has no place because Deathrite Shaman can be cast with Swamps so adding a shockland would just slow the deck down or force you to lose life for no reason. The Nightveil Specter is a good option for its devotion but when you look at it from a game winning scenario using this instead of Lifebane Zombie could cost you to just have a 2/3 flyer and when you look at the lifegain provided by this deck taking damage is fine as long as you are doing more damage. Thoughtseize is good for destroying creatures and other nonland spells but this would mainly be only for a creature heavy deck which this should not be that afraid of since it runs some heavy hitting creatures. The Duress are there for the Esper Control matchup where this deck gets stomped on. I'd say Desecration Demon is still this decks best 4 drop when it comes to choosing between it and Disciple of Phenax .
Any more ideas feel free to comment and I should respond in a timely manner.
Look into Dark Prophecy card advantage and good devotion.
I have built a mono-black devotion deck also. I ran it at the last FNM and it did quite well. I have found that Strionic Resonator actually get's pretty good mileage when used on Gray Merchant of Asphodel or Abhorrent Overlord . My deck includes many other triggered effects but doubling either of these two is a BIG DEAL!
My deck also mains one Erebos, God of the Dead but I have more in the side because I do not want healing decks to make my job harder than it has to be, besides Erebos, God of the Dead is a very big, very angry guy once you have 5 devotion. While is active effect isn't great my deck often has much more life than it really needs so I've gotten some use out of it.
You should run at least 2 Nykthos, Shrine to Nyx . Supposing you have one in your hand and one on the field you can active the one on the field for mana equal to your devotion, THEN play the second one (sacrifice only the first one that is tapped out) and then activate the second shrine for even more mana, you lose very little that way and the shrine is excellent at ramping into a stronger mid game.
For more ideas check out: Triumph of Darkness! (Purest Black Devotion!)
I like the the Dark Prophecy card idea Ti22_HipHero and I have seen this being used in other mono black pro decks.
Zacoly thanks for recommending Strionic Resonator because it honestly goes perfect in this deck and helps better round out the mana curve. I think that this will be a definite 2x or 3x in this deck when I update it. The reason I have Erebos sideboarded instead of mainboarded is that I would rather drop a turn 4 Desecration Demon instead of it and if I'm playing against g/w aggro then they will probably sideboard in Unflinching Courage for lifegain to which I'm putting in Erebos at the same time.
Thanks for the ideas and don't forget to plus one.
Recently updated the deck. Here's whats new.
This really helped to round out the mana curve and some people may argue the 4x Nykthos but it allows for huge turn 4 and 5's. The extra removal also helps the creatures get through.
Underworld Connections is also great for devotion. and your creatures don't have to die.
This is a great deck! It's very different than a lot of black devotion decks, and there are pros and cons to it. Firstly, it does tons of damage if you can get to that 7th turn or so.
However, getting to that 7th turn without being too far behind seems to be a struggle. I think you should add some removal in there (particularly Doom Blade ) or Hero's Downfall just to give you some early presence. Also, you have Pack Rat but no other rats than the Packer himself. There are definitely some good rats that would work wondefully here, Typhoid Rats comes to mind.
I really like the Nightveil Specter s you have in here, they work really well in this deck.
Thanks xantos that is the really the idea of this deck. The removal is a very good suggestion but the reason why I sacrificed it was for pure board presence because if my opponent is playing creatures as well than I think I can out race him. If they are playing removal then I just need to hope I can outjam their counter spells and removal. Also, I don't need worry about planeswalkers like Elspeth, Sun's Champion because most of my creatures having flying and by the time they get it out my board should be in a pretty good spot. I plan on keeping this deck standard but Typhoid Rats would be a good suggestion if I play it casually with friends.