1. Phyrexian Arena > Underworld Connections...however not only is Underworld Conections uch, much cheaper but they give me control over my draw/life loss at the cost of being more clunky.
2. Innocent Blood & Barter in Blood: More cost effective than single target removal but hits my creatures as well; is the trade off worth it or should I go with targeted removal (or potentially go creatureless)?
3. Dark Ritual: It wants to be Bloodchief Ascension...it will likely be my first upgrade!
I think, you should focus more on the Gray Merchant for the life drain. With all those sac effects in the deck, the Merchant will find its way into your graveyard for sure, and with black being THE reanimation color, you can get double duty out of it. Beacon of Unrest for example, can thus function as additioal copies while also giving you the option to reanimate the big bombs your opponents had to sacrifice. And the reshuffle clause makes you have a virtually infinite amount of that card to draw into, even if its just one or two actual copies.
Another approach would be something like Skull Collector to bounce and replay it every turn, while providing you with a good blocker and a good amount of devotion. You could then also run permanent based spot removal like Skinrender for repeated killings and yet more devotion.
Edit: Phyrexian Metamorph can also copy the Merchant and while blue can be played in a monoblack deck. The mana cost is copied as well, so it's not detrimental to devotion.
Nice deck choice! MBD has won me tons of games, but it can vary wildly based on budget and your group's meta. Thankfully the shell is so versatile that it's easy to construct a deck that is fun, strong, and relatively inexpensive (I like to keep my decks <$50). Anyhow, my thoughts on your current build:
Ditch the Dark Rituals. They are dead draws most of the time, and are only useful to power out a game-ending Exsanguinate.
Too many sacrifice spells that hurt your gameplan. You'll demolish your board and weaken your Gary triggers. Another poster mentioned it, but consider Plaguecrafter instead of Barter in Blood. It'll lower your curve a bit and nab a planeswalker from time to time.
Too much card draw. I usually run about four draw spells, which has been sufficient. I really love Read the Bones
4 Leechridden Swamp
4 Basilica Screecher
4 Vampire Nighthawk
4 Gray Merchant of Asphodel
4 Innocent Blood
4 Underworld Connections
4 Exsanguinate
4 Syphon Mind
4 Barter in Blood
My initial thoughts are as follows:
1. Phyrexian Arena > Underworld Connections...however not only is Underworld Conections uch, much cheaper but they give me control over my draw/life loss at the cost of being more clunky.
2. Innocent Blood & Barter in Blood: More cost effective than single target removal but hits my creatures as well; is the trade off worth it or should I go with targeted removal (or potentially go creatureless)?
3. Dark Ritual: It wants to be Bloodchief Ascension...it will likely be my first upgrade!
More mana though.
My meta: 3 or 4 player free for all, anything goes but boring games or broken decks cause a vote to end that game.
Another approach would be something like Skull Collector to bounce and replay it every turn, while providing you with a good blocker and a good amount of devotion. You could then also run permanent based spot removal like Skinrender for repeated killings and yet more devotion.
Run enough creatures and Oversold Cemetery fuels your hand further.
Edit:
Phyrexian Metamorph can also copy the Merchant and while blue can be played in a monoblack deck. The mana cost is copied as well, so it's not detrimental to devotion.
Former Rules Advisor
"Everything's better with pirates." - Lodge
(The Gamers: Dorkness Rising)
"Any sufficiently analyzed magic is indistinguishable from science."
(Girl Genius - Fairy Tale Theater Break - Cinderella, end of volume 8)
Here's what I'm running currently:
16x Swamp
4x Vault of Whispers
4x Darksteel Citadel
Creatures (21)
4 Cuombajj Witches
2 Darksteel Myr
2 Gonti, Lord of Luxury
4 Gray Merchant of Asphodel
4 Phylactery Lich
1 Ravenous Chupacabra
2 Sangromancer
2 Vampire Nighthawk
2 Gonti's Machinations
3 Pestilence
1 Haunted Crossroads
Sorceries (9)
2 Battle at the Bridge
3 Exsanguinate
2 Read the Bones
2 Syphon Mind