doctorhydrogen

Nykthos, Shrine to Nyx will probably benefit from all those black mana symbols.

If you're gonna only run one enchantment (Rhystic Study) why not just go all the way and replace it with a card-draw artifact like Mind's Eye or something and then run some enchantment hate like Tranquil Grove or Paraselene to eff over everyone else.

You have no targeted enchantment/artifact/creature removal. Someone slapping a Pariah on your Avacyn will ruin your day (or playing a Story Circle, Eldrazi Monument in a token deck, etc). I'd find a slot at last for Return to Dust, and probably Revoke Existence, too.

Crackdown can really screw over anyone else not playing mono-white.

Since you have a built-in sacrifice engine in Grimgrin, I'd find a slot for Dictate of Erebos, too, and make everyone else sacrifice creatures whenever you do. Grave Pact would also work well (and personally I'd consider running both) but Pact is about ten bucks vs. about 90 cents for Dictate.

Unholy Grotto would function like a second Volrath's Stronghold.

Same thing happens to me with every deck I try Black Market in; it gets some absurd amount of counters on it and they wind up not really mattering.

The more creatures that kick six tokens in a swing the merrier, I say.

Is Attrition worth running? I ran it for awhile in my variant on this but it always seemed like between Martyr's Bond, Grave Pact and Dictate it was redundant.

Lotta one-mana elves you could easily tutor up with Citanul Flute.

Circle of Despair might be worthwhile, too.

Indeed you do.

Teysa Orzhov Scion and Ogre Slumlord could puke out a ton of tokens on Apostle sacc.

Dictate of Erebos as another Grave Pact effect?

Extinction would function as a second Engineered Plague

Yeah, I'd rather run Extinction over Plague Sliver. It all tribals not just slivers, and worst case you can still use it like an expensive Murder to kill something by naming that creature's type.

I'd call Deathreap Ritual an auto-include in Golgari colors. It draw at least one card a round. It's not going to be as bursty as Sign In Blood but unless you're playing 1v1 I'd say more often than not Deathreap is going to draw you a lot more cards than Sign while also helping with Devotion.

It's not a sexy card or anything but Grim Feast is brutally efficient. Note the oracle text is ALL opponents. I've had a board wipe generate me 100+ life with it before.

Isn't Murder strictly better than Rend Flesh? Personally I'd be tempted to just run Sever the Bloodline in that slot. For me at least it's worth one extra mana to be able to hit a pile of tokens or two different people running Nylea or something, plus it exiles so it hits indestructible stuff, plus it has flashback so you can use it again late game. That's my meta, though, yours may be such that instant speed is more valuable than all of that.

Victim of Night is fine but I'd rather pay 1 more and run Hero's Downfall and be able to kill anything including Planeswalkers.

Elbrus is unfortunately considered a black card for EDH purposes (Sheldon from the rules committe comments about half way down this thread: http://smtp.dragonhighlander.net/Forum/viewtopic.php?f=2&t=11327&sid=c2ac1896b9dd471cf2f0662fc0bcf7a9)

Back to Basics and Quicksilver Fountain destroy people if you're mono-blue.

Damnation as an amazing card at 4 mana . . . but I don't run it anymore because I see too many Theros gods, Tajic, Avacyn, regenerating Thrun, etc. Black Sun's Zenith kills all of that stuff where as Damnation seems to miss half the board. YMMV as I would imagine that depends highly on your meta.

IMO you need some way to deal with other people's enchantments and artifacts or a token deck with Eldrazi Monument and Doubling Season or Sigarda deck running Ghostly Prison and Sphere of Safety is going to lock you out. Krosan Grip is great because it can't be countered or responded to, and I'm a big fan of Unravel the Aether and Deglamer because they deal with indestructible stuff and prevent graveyard shenanigans.

Also, with almost a third of your deck being faries, Call of the Kindred will get you a free creature into play pretty often.

Dissolve is better than Cancel at the same casting cost. Hinder is too, but it's 4 bucks or so, where as Dissolve is like twenty cents.

Depending on how much of a jerk you wanna be, Quicksilver Fountain and Back to Basics can shut multi-colored decks down completely.

You also don't have any cards to deal with someone else getting ahead. An overloaded Cyclonic Rift can (and does) save the day pretty often, and Wash Out and Inundate are pretty decent, too.

Hinder > Cancel

I'd find a spot for Spin into Myth, too. Putting someone's commander or Ulamog or whatever on the bottom of their library can be invaluable.

Dismiss into Dream is a monster in Derevi. In addition to preventing everyone not you from equipping, enchanting, etc any stuff you can also destroy anything of an opponents you tap with Derevi. And since it's a sacrifice effect it even works on indestructible stuff.

Birthing Pod can be pretty solid here since you can pod Derevi to tutor up your 4 CMC creatures into play, then replay Derevi for 4 mana.

Bramblecrush has the same CMC as Creeping Mold but also hits Planeswalkers.

Detention Sphere has the same CMC as Oblivion Ring (though it requires two colored) but has the ability to hit all targets with the same name. It really doesn't matter often, but I've had enough games where being slightly more difficult to cast is worth having the ability to take out 15 tokens in one swoop, or the two different Jaces or Erebos' in play, etc.

By the same token, Supreme Verdict is an amazing wipe in that it's uncounterable. I'd run it over Wrath for sure.