You ever considered Attrition or Mind Slash as ways to deal with opponents? Some other cards I think would be good in here would be Grave Titan , Gray Merchant of Asphodel , Dark Prophecy , Sepulchral Primordial , and Sheoldred, Whispering One .

@Saithor thanks for the comment. Both Sheoldred, Whispering One and Grave Titan are on my acquire board. Dark prophecy used to be in here, but it was killing me. Attrition could be good.Both Gray Merchant of Asphodel and Mind Slash seem underwhelming. Especially Grey merchant, Tokens don't give any devotion so it's not very good.

The primordial is good, I'll try to add it.

Liliana of the Dark Realms and Sorin Markov are great EDH walkers, Phyrexian Obliterator is disgusting in any format, and Whip of Erebos is great for skyrocketing your life total

I have the whip in the build, obliterator died right away and was not really worth it, that liliana is lack luster and isn't actually that great in edh and I might add sorin because win con's are good.

The problem with Phyrexian Obliterator in EDH is that nobody is ever in a million years going to block it or otherwise damage it. 5 damage is not enough of a threat in a format that starts you off at 40 life, so what you're left with is just have a 5/5 for 4 with no utility beyond it being basically unblockable. Inconsistent, easy to remove non-hasted creature beats doesn't really merit a slot in most decks. There are even times in EDH when your opponent will be more than happy to sacrifice creatures. The only value I got out of him in the dozen games I played with him was having him beef up Gray Merchant of Asphodel .

I like Liliana of the Dark Realms in mono-Black EDH. Early game she'll make sure you hit your land drops, her Ult is great but not quite intimidating enough that people will go out of their way to cut her down, and if you pull her late she can be either removal or a blowout buff to swing in for lethal. In terms of sheer power though I'd probably rather see a dozen other cards, including Sorin.

I'd run Mind's Eye over Staff of Nin . The plink in Staff of Nin doesn't really come close to the sheer card advantage Mind's Eye can generate. I was skeptical of Mind's Eye at first because you have to pay for each draw, but in practice in EDH it's basically draw for every land you have untapped at the end of your turn. It has that Consecrated Sphinx quality where it doesn't have to survive a round to get you anything, it pays off on their draw step and bonus points if your opponents are drawing lots of cards. With all the mana doubling in mono-color and specifically the mana bonanza that is mono-Black their Stroke of Genius is your Stroke of Genius.

I might play mind's eye...I'll try it out at least. and thank you for better answering why Obliterator was removed. it was dead on.