One of my first thoughts is that because of all the high mana cost cards, many opening hands could be a little lofty for the first 3 turns.
On top of that, there are only 7 creatures that cost 3 mana or less. Most of those cheap creatures are powerful though - the 4 Ruthless Rippers can buy the deck some time. I'd definitely want it in a starting hand.
I think with so many single cards, the deck has too many things it can't depend on, and too many that it can't. Too many low probabilities.
An emphasis on pulling cards from the graveyard to your hand/library/battlefield but nothing that enables you to discard the high mana cost cards from your hand so that they can be put on the battlefield.
No way to
accelerate number of Land = it will be a long wait for all those expensive cards.
Because most of the "return card from GY" cards put cards into your hand, I see a lot of cards you can't afford to play cycling in and out of your GY and hand for no reason. They would work well with the Ruthless Rippers though. If you had even 2 of them out and could bring them back into your hand after they died it would be a nuisance.
I feel like the deck has a couple possible directions to take.
The cards that allow you to draw cards might conflict with high mana cost cards making up part of your hand - which means you might have a good chance of discarding cards - but I guess you could return them to your hand, but then just discard them again and ona nd on, but what is the goal? This is just theoretical though, we need to play-test to see how relevant any of my jabbering is.
Liliana's Reaver - pretty nice 4 drop (fair draw chance)
Drana - question of mana - is this card as relevant as your other high cost creatures (low draw chance)
overseer - I think its just too expensive (low draw chance)
palace siege - u alrdy have enough "return from GY to hand" and I feel like with only 1 in the deck it won't be relevant enough (low draw chance)
profane command - conflicts with the more relevant high cost cards in your deck (low draw chance)
quest for the gravelord - could get 3 more (low draw chance)
read the bones - meh (decent draw chance)
grasp of darkness - not bad (decent draw chance)
master of the feast - maybe you can find a flyer that more directly compliments the goal of your deck (low draw chance)
Soul of innistrad - again, you might end up with more cards in your hand than you can handle (low draw chance)
Sorin - seems like more of a novelty in this deck (low draw chance)
Ob - seems alright for survivability (low draw chance)
archfiend - pretty good for turning the tide or controlling fights (low draw chance)
nightmare - being a 6/6 flyer for 6 is alright, but id rather play cheaper flyers that I can enhance (fair draw chance)
gravepurge - if you're going to go with a graveyard style deck, u may want more of these (low draw chance)
gisa - great if you can find a way to get the high mana cost creatures out quicker (low draw chance)
malicious affliction - useful, should get 4 (low draw chance)
grave titan - strong card (low draw chance)
debilitating injury - should have at leats 1 more if keeping in deck (low draw chance)
bile blight - id choose these over
grasp of darkness and remove grasp for something like more
wight of precinct sixnatuko shade - not bad, coul;d use 2-3 ) low draw chance
Ruthless - these are awesome, however I feel like they are the deck's crutch
promise of power - could be a game winner if you have enough cards in your hand from pulling cards out of the graveyard 0 the thing si you could go way over maximum hand size with the cards u have in your deck. finding some cards that let u have no max hand size might make this work like a charm. could be a direction for the deck. (low draw chance)
Wight of Precinct Six - could really sustain your deck, especially in bigger games - get more (low draw chance)
liliana vess - the most relevant plainswalker in the deck because of putting all graveyard creatures onto the BF (low draw chance)