I've been wanting to build a GB EDH deck for years now, and I have with Nath, Glissa, and Savra, only to quickly dismantle them in disappointment, granted, I didn't buy or proxy cards at the time and only used the budget cards I had so that might have been a factor, as well as all of those decks having an elf tribal theme to them. My monogreen Ezuri deck almost ended up green and black, but aside from the cool spells black offered, it didn't offer enough in the elf tribal department for me to warrant it. Essentially the deck would've been a lot of green elves, with about 3 black elves, and then a bunch of good black instants and sorceries, the deck idea felt awkward so I abandoned it. Meren, and to a lesser extent, Mazirek were spoiled for the 2015 Commander decks and I was quite pleased.

Originally when I first read Meren, of Clan Nel Toth, I thought her ability that gained experience counters was linked to sacrificing creatures, so the first version of the deck put in a lot of sacrifice themed stuff. Honestly I'm kind of disappointed it only cares about your creatures dying, and not specifically being sacrificed. I quickly scrapped that idea and them and started putting in just generally better cards to utilize her ability without restriction. Some cards will remain in the deck for a little longer, but it then becomes obvious there was a sacrifice theme intended from the beginning, but without trying to stick to that theme now, they will eventually be replaced unless testing proves them to be on par with the rest of the cards.


Land base is atrocious
I always feel it's awkward that 3 color Shard or Wedge decks have better and more stable mana bases than two color enemy paired decks. I don't like using a bunch of fetchlands in decks, but this one might warrant it in order to smooth out the mana base. The deck goes pretty far into black and green so it's been a challenge to get double black and green by turn 3 or 4. Most of the dual lands enter tapped which hurts, but I don't think basics help this problem. I don't like Vivids but I might need to rely on them. Rupture Spire and Transguild Promenade are a necessary evil as well. As for as colorless lands, Temple of the False God is pretty good, as well as Reliquary Tower. I've never used High Market before in a deck, it seems good in theory though, but with less reliance on a sacrifice theme, it might not do much, other than allow me to kill a creature on my turn in order to get it back out with Meren, I just don't know yet. Grim Backwoods, I hated this card when it first came out, it's a cool design but it costs too much I feel, sacrificing a creature is already a huge cost, on top of paying FIVE mana to draw A CARD, the weakest in the cycle in my opinion, and again, another sacrifice themed card that I don't think is worth including outside of sticking with that type of theme. Svogthos, the Restless Tomb, another card I've tried sticking in multiple decks, only to find it underwhelming. Yes creatures are going to be hitting my graveyard a lot, but I'm not sure I want just a big creature that costs 5 mana to use, I don't think I'll be putting Lord of Extinction back in the deck, and that was the biggest creature ever. Too many colorless lands it seems like.




Creatures that sacrifice or destroy
The main ones

Shriekmaw - Staple in black decks, it can either cost 5 or 2, and evoking it can add synergy with the deck.

Fleshbag Marauder - Another auto-include for black decks. A creature that can be reoccurred and force everybody to sacrifice again and again.

(Merciless Executioner) - Not in the deck, but another 3 drop that is a functional reprint of Fleshbag Marauder. I've seen some lists running both, I'm not sure I want another slot for that at 3CMC. It does create consistency if I don't have access to Marauder though. I'll test more, maybe it'll get into the deck.

Slum Reaper - A Fleshbag Marauder for 4 mana instead of 3. It gains +1/+1 for the extra mana, not super relevant but definitely welcomed. In monoblack I only use Marauder, but I think this deck warrents the Reaper's inclusion, as well as filling in a spot on a Birthing Pod curve.

Others
Predatory Nightstalker - 5 mana 3/2, not super impressive. When I first put the card in, I thought it said each opponent sacrifices a creature, meaning it was one of the creatures that didn't force me to sacrifice as well, however it only says target opponent. It might still be okay though because then it's a sacrifice and I'm not losing anything. Creatures that sacrifice can be seen as stronger, but giving an opponent a choice is usually seen as unfavorable, where destroy target creature would be better. Unfortunately, a lot of creature based destruction on bodies has restrictions, such as Shriekmaw's "nonartifact, nonblack creature" clause.

Big Game Hunter - 3 mana to destroy target creature with power 4 or greater on a body. This format is filled with big creatures and this is so cheap on a body with hardly a restriction. There are some problematic creatures with less than 4 power this can't deal with, but I think overall, this is pretty solid in theory. Will test more.

Shadowborn Demon - 5 mana, 5/6 flying demon, seems on part. When it comes into play I can destroy target non-demon creature. Demons are usually pretty big and this format sees some of them played on a regular basis, I'm not sure if that restriction is bad though. What does hurt this card's playability for me is that it's not a may effect, and I need six creatures in my graveyard during my upkeep or I am forced to sacrifice a creature. Again, if Mazirek was the commander, the sacrifice would be welcomed. It is the cheaper option compared to the next card for creature removal.

Overseer of the Damned - 7 mana for a 5/5 flying demon. It's trigger is a may ability which is a plus. It also has another ability that I think makes it cost more mana than Shadowborn Demon. If a nontoken creature an opponent controls dies, I get a 2/2 zombie token into play tapped. The token creation is nice, but honestly, I would prefer this to be cheaper at 5 or 6 mana with no token ability but whatever, it is the most unconditional creature killing creature in black that I've found. I'm just worried I won't be able to cast it soon enough to death with a creature, but who knows.

Cards on the chopping block (needs more testing)

From Beyond - I have Bitterblossom at 2 and Awakening Zone at 3, I'm not sure if this enchantment at 4 is too much. Like Awakening Zone, it does provide creatures with a free sacrifice ability and generates me some extra mana. In theory, it's good and fits the curve, I just don't want to draw too many of these effects late game and them be dead. On the upside over Awakening Zone though, these tokens are 1/1s instead of 0/1s.

Grave Pact - I know it's really good, I just can't seem to draw into it, nor is it ever going to be a main tutor target. In theory it's good, or in a semi-winning or winning board state it's amazing. Needs more testing though.

Dark Prophecy - While going through cards I had, I came across this one, and it seemed exactly what I wanted. The cost is a little restrictive but with enough land searching, I should BBB pretty early.  This is good because the deck want's creatures to die, it's very black in the sense that it's not a may effect, and I lose 1 life. There was another enchantment I came across from Battle for Zendikar called Vampiric Rites. It only costs B, and I can pay 1B to sacrifice a creature to gain 1 life and draw a card. So now, instead of losing life, I gain 1 life, and it can act as a sacrifice outlet which I seem to need a few more of. I'm not sure I want to be spending that mana every turn when I usually seem to be tapping out, yes it's a sac outlet and I gain life, but Dark Prophecy is free card draw.

Whip of Erebos - It makes sense that this would be in a reanimation style type of deck. The downside is that I don't necessarily want to be exiling cards from my graveyard that I could potentially use later. The upside is that I can use it more times than a spell, and with all the lifeloss this deck seems to inflict upon me, lifelink for my creatures might be needed. Haven't drawn and thus played with it so I'm on the fence until more testing occurs.

Darksteel Plate - Amazing in theory. The first version of the deck relied heavily on Meren being in play, so making her indestructible to get as much value out of her end of turn trigger was a must. Now the deck shifted away from depending on her, to utilizing her for advantage, but she isn't needed to win. I haven't gotten a chance to test this either. I honestly feel the lack of white for Stoneforge Mystic and Enlightened Tutor kind of hurt the deck, despite being in black and having access to all the best unconditional tutors in the game, I feel like I don't want to overload the deck with those tutors, but the conditional ones are alright for whatever reason in my mind, I guess I like the restriction. So, needs more testing.

Doomgape - one of my favorite GB cards all around, in art and mechanical design. Was in to be an upkeep sacrifice outlet. The lifegain didn't hurt as well. 7 for a 10/10 trampler is just awesome. I can always choose to have it eat itself and just gain 10 life instead of eating everything else first. I really want this card it, but like usual, it might not make the cut. Maybe if Mazirek was the commander instead, it might be a better fit in. Needs more testing.

Gleancrawler - Another card I've always wanted to play with, and in theory, synergizes with the death/sacrifice theme of the deck. The idea was to have it and Meren out, sacrifice a bunch of creatures, stack the triggers to that Meren gets a creature into play and then Gleancrawler returns all the others that died to my hand to recast again. Cool design and theory but I need some good 6CMC creatures and I don't feel like this does enough, and it's not even really a combo of sorts because I need so many pieced. Yes, I could sacrifice something to Birthing Pod and get this, but I don't know, it seems less amazing in practice than in theory.

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Outs
Doomgape
Gleamcrawler
Shadowborn Demon

Ins
Greenwarden of Murasa
Tooth and Nail
Journey to Eternity

Proxies
Bitterblossom
survival of the fittest
pernicious deed
darksteel plate
Tooth and Nail
Damnation
buried alive
demonic tutor
bloodghast
kokusho, the evening star
predatory nightstalker
Overgrown tomb
woodland cemetery
llanowar wastes

cards to add
Ravenous chupacabra