I like a lot of what you've done here. Just keep in mind that Horobi's trigger goes off as soon as a creature is targeted, and will thus resolve before the effect which targeted it. This means that while he's on the board, effects like Duplicant, Necrotic Plague, and Enslave will become little more than glorified overpriced kill spells.

Inversely, if my interpretation on this matter is accurate (I'm not 100% sure on this though), Devour in Shadow will become stronger, as its target will have been destroyed before it resolves, causing you to lose no life.

I briefly touched on it before, but with Horobi as your commander, I highly recommend Touch of Darkness. Obviously it does little without him on the board, but it can be absolutely devastating with him on the board.

Cauldron of Souls can produce a similar effect every turn, but it costs quite a bit more. (Remember, the creatures are destroyed by Horobi before they gain persist) Though I can't recommend this quite as much due to a combination of the mana cost and the target it paints on your face. If you think you can hold the lockdown though, go for it.

Overall though this looks pretty fun. :)

The way I play horobi is lots of targeting spells to clear the board, like Touch of Darkness and Cruel Feeding, and then a bunch of one drop targets. Aphotic Wisps Death Wind Disfigure Eye Gouge Lose Hope Tragic Slip Virulent Wound Cabal Trainee Shambling Goblin and so on. I also like Avatar of Woe, cause it's easy to get cheap with a deck like this.

Also, this is commander.Cauldron of Souls costs five. You don't care, that's not bad.

One drop targets are nice, but you'll still only go one-for-one with them at best. Multitarget is where it's at. Cards like Cannibalize which take out two for just two mana, Ashes to Ashes or Reckless Spite which hit two for only 3 mana.

If you're really going to profit off of Horobi's effect, you need to be doing more than trading one card for one card at a time. It's all about the card advantage. One for one at instant speed can be useful in dire situations, but it really shouldn't be what you build around.

Without Horobi, Cauldron of Souls forms a neat little combo with Mikaeus, the Unhallowed. It can also save your board from a wipe. With Horobi online it is brutal.

Hey Tyrant-Thanatos, Flagellum. Thanks as always, and also thanks Tacticsninja16782 for the thoughts. I've been trying to get the balance between effects that synergise with Horobi, and ones that still offer strong value when it's not in play. I'm kind working to the assumption that if it hits play it probably won't be there for long. Made a few tweaks, mainly dropping Endless Whispers but also a few of the cards like Duplicant that don't synergise well with Horobi.

Avatar of Woe is a great mono black card, but we're trying to go specifically for mono utility creatures that affect the board state so not sure it fits here although I do own a copy. I've benched Phyrexian Obliterator and Grave Titan for the same reason.

I think in terms of things that 'target' as you say, we want stuff that hits multiple creatures, and that Horobi greatly enhances. I did some searching on gatherer, and dug out the following:

Shambling Swarm. Without Horobi it's got the potential to hose 3 x tokens or a single 3:3. With Horobi in play its 3 x Murder. And a potential Grave Pact or Dictate of Erebos trigger.

Mogis's Marauder. At worst a chump body to trigger Grave Pact that gives any creatures we have intimidate and haste. At best, with Horobi out a wrath equal to our devotion.

Liliana of the Dark Realms. Her -3 becomes Murder with Horobi out.

Contagion. Potentially -1 life and exile a card to Murder 2 x creatures

Nefashu. Conditional on attacking, but can be up to 5 x Murder with Horobi out. Fragile, and only useful for token hosing without Horobi.

Blightcaster. Synergy with our large number of enchantments. Can't see it sticking around on the board long though.

Consumptive Goo. High mana cost to activate. We're not that interested in keeping creatures around.

I also like Sorin Markov, and his + ability suits the deck, and synergises with Horobi, but I am slightly wary that the 'change life to 10' breaks the social contract of EDH, so I may go Liliana Vess, Liliana of the Dark Realms, and either Ob Nixilis Reignited, or Ob Nixilis of the Black Oath. Black oath may be useful life gain.

Cannibalize. Goes from a useful exile spell to a 2 x Murder for 2cmc. Ashes to Ashes is useful either with or without Horobi.

I've added Moonlight Bargain as a card filtering instant. Although I am tempted by Vampiric Tutor instead, although we are running Demonic Tutor, Diabolic Tutor, and Liliana Vess. May drop Diabolic Tutor for Vampiric Tutor.

I would trade the Diabolic Tutor for the Vampiric Tutor, especially if you already own one.

Consumptive Goo does seem to have a hefty activation cost if you're looking to kill more than one a round with it. (and I have my doubts it would live any longer than that)

I've had a pretty good record with Nefashu in the past, without Horobi. His effect seems pretty token-hate to begin with, but it's really versatile and can handle a lot of annoying utility creatures. (here's looking at you, Elves)

Honestly I don't know how I forgot Contagion. Such a wonderful card.

Shambling Swarm seems like a pretty useful creature. I've never run it before but, even without Horobi online, three -1/-1 counters distributed? That sounds pretty strong. I mean obviously a 3/3 for 4 isn't exactly the deal of the century, but with the success I've seen from cards like Festering Goblin, it's hard not to see potential there.

Some more interesting combos you can do with Horobi:

Horobi, Death's Wail + Karn, Silver Golem + Liquimetal Coating + a targeting ability/spell= dead enchantment/artifact/planeswalker/land

Gate to Phyrexia + Liquimetal Coating = dead enchantment/artifact/planeswalker/land

Looping Kokusho, the Evening Star/ Gray Merchant of Asphodel with recursion spells or with Cauldron of Souls + Mikaeus, the Unhallowed (without Horobi) and a sac outlet.

Just in here to plop my old card for the day!

Sure it's a tiny bit on the expensive side and could possibly hurt you too, but I mean, once you drop that bugger, HOLY -insert any curse-, people will start panicking. Because, not only can you choose to destroy lands, everyone can.

If Karn is hard to find or unavailable in your area, Xenic Poltergeist makes for a budget alternative. It's just intriguing that Horobi can use shenanigans to destroy enchantments and artifacts which generally has problems with.

Hey Tyrant-Thanatos. Made those tweaks. Dropped Crypt Ghast for Shambling Swarm. Couldn't see the ghast sticking round the table long enough.

Flagellum. The other idea was running Chainer, Dementia Master as I have a copy to recur stuff from the graveyard.

Eiti3. Was eyeing Kormus Bell earlier today. May be a fun include, but I've typically stayed away from land destruction.

Hey Draw_Wurm,

I found your deck over at the "Advertise your Commander Deck" fourm. Your deck looks really neat. I've never seen Horobi, Death's Wail in the Command Zone before, but Horobi is a staple in my friends Vhati il-Dal deck so I'm not totally unfamiliar with the card. I am familiar with mono black because of another friends Liliana, Heretical Healer  ^Flip deck, and if you don't plan on casting Horobi that much I think I'll be in a pretty good spot to help you. Anyway I'll try to do my best.

The first thing I noticed about your list was that your maybe board is huge, so I'll start by talking about that. Here are the cards I think really aren't good enough and should be cut from the Maybeboard:

1. Chainer, Dementia Master: It's just too easy for someone to remove Chainer and suddenly really set you back.

2. Corrupt: A six mana sorcery should really have a better effect than that. Maybe if it drained each opponent that would be better. As it stands it's just weak too weak. A good scenario is that you deal one out of 4 opponent 10 damage and gain 10 life. There are way better things I would do for 6 mana at sorcery speed.

3. Diabolic Tutor: Much worse than many other tutors. If you want a tutor just pick almost any other black tutor and you'll be better off.

4. Homicidal Seclusion: I'm not saying this is a bad card, I'm just saying it's too conditional. There will be better things to do with 5 mana.

5. Lake of the Dead: In my playgroup this would be a huge Strip Mine target and wouldn't last a turn. Doesn't seem worth it.

6. Lashwrithe: A big vanilla thing doesn't seem that good to me. it's not like you're running Skithiryx, the Blight Dragon as your commander and this would have somewhere useful to go.

7. Last Laugh: It seems like this doesn't acutally do anything benificial for you. Some decks play universal effects like Winter Orb because they can play through it better than their opponents and it's a relative advantage. This deck doesn't seem to get any relative advantage from this universal effect.

8. Nameless Inversion: I don't see what purpose this has. It seems weak as a pump spell and a kill spell.

9. Nether Void: It's a neat card but this doesn't seem like the spend $300 on one card type of deck.

10. Syphon Soul: It's a little weak. It's a fair effect for the CMC but honestly I feel like its just not worth the card slot. Wild Nacatl is great for its CMC but Naya commander decks don't run it because it's just not worth the card slot later in the game.

11. Toshiro Umezawa: You're only playing 8 instants and each one can only be used this way once. Seems like more often than not you're not gonna be able to take advantage of this card.

12. Tyrant's Choice: 4 life just isn't that relevant in a 40 life format. You could occasionally talk the table into making people sac stuff but that seems like a corner case. It's can't be easily recurred. It's not worth the card slot despite being a decent effect for the mana cost.

13. Unstable Obelisk: If you're looking for an effect like this I think Lux Cannon is a lot better.

Looking at your list I would cut the following cards for some of the cards remaining on your Maybeboard:

1. Night of Souls' Betrayal: Not really sure why this would be good in your deck in particular. You have better options in the Maybeboard

2. Everglades: This card is bad. It's a Strip Mine target and it doesn't do enough to be worth not counting towards Cabal Coffers. maybe replace this with a basic instead of a card from your maybe board.

3. Mana Vault: If your looking for effectivly one time ramp (which this is), then you should be running a Dark Ritual or Cabal Ritual. however, I dont think one time ramp is what you want and I'd pick from your Maybeboard to replace this.

4. Reliquary Tower: It doesn't feel like you're drawing enough to make this worth while.

5. Ambition's Cost & Ancient Craving: There's better and more repeatable ways to get card advantage in black.

If you provide more info on your playgroup, your how the deck has been preforming, how the games would ideally go, etc. I'll be happy to help you even more.

Lmk if you have any questions!

Hey TwentyFive_Shmeckles. Thanks for that detailed feedback. Really appreciate it. To give you a bit of background, this deck started out way back as the 'Sworn to Darkness' 2014 pre-con and I've slowly been evolving it and tweaking it from a generic 'black good stuff' build to something more focused. I've dropped cards like Geralf's Messenger, Nether Shadow, Bloodghast, which were self-recurring bodies and gone for creatures that affect the board state.

It's designed to be a multiplayer deck, and tries to play interesting cards that change the dynamics at the table. It's not designed to make anyone swear, so no infinite combos, but for people to see it as an interesting puzzle to play around. So far, cards like Temporal Extortion and Head Games have made people go: "cool effect". Vulnerabilities have been colourless creatures and Voltron commander damage.

I've updated the deck description with rationales for the current card choices. The maybe board is either black good stuff cards like Grave Titan and Phyrexian Obliterator which I own but don't fit, alternative wraths, tutors or political cards or enchantments like Polluted Bonds that I liked but couldn't quite find the spot for.

Cauldron of Souls is hilarious with Hirobi.

Chainer works just have a sac outlet ready if you recur your own. If you stick to opponents creatures then it's fine. Mimic Vat (in your maybe list) can copy a big threat or alternatively, imprint Horobi should the tax get too high.

Been thinking about a few other cards with Horibo synergy. Mainly colourless cards that target creatures:

Lands

Shizo, Death's Storehouse. Produces . With Horibo, to kill target commander.

Urborg. Produces . With Horibo to kill.

Cabal Pit. Lifeloss, but an additional removal spell with Horobi at Threshold.

Maze of Ith\Mystifying Maze, go from defensive to tappable kills.

Tower of the Magistrate. Useful protection into a kill.

Artifacts

Echo Chamber. Copy their creature and kill it at the same time. Opponent chooses the creature.

Helm of Chatzuk. With Horibo to kill target creature. No real utility without.

Baton of Morale\Sacred Armory. With Horobi to kill target creature. No real utility without.

Thran Forge. Higher cost, better utility.

Power Matrix. Without Horobi powers up one of our or opponents creatures. With Horobi becomes a Murder.

Soldevi Golem. 5/3 that kills a creature when it untaps

Serrated Arrows. for 3 x murders.

Sentinel. Kills pretty much anything it can block with Horobi out.

Crenellated Wall. Blocker. to kill a creature with Horobi.

Contagion Engine. Potential wrath and Planeswalker boost.

Clockwork Hydra. 4/4 for . With Horobi takes a creature with it when it attacks or blocks.

Belbe's Armor. With Horobi, kill. Without, boost a creature on defense.

Barl's Cage. cmc cost, but a useful effect in Horobi's absence.

Grim Poppet. cmc for 3 x Murder at instant speed and a potential 4/4 blocker.

Erratic Portal. Tappable Murder with the ability to bounce our own creatures back to recur ETB effects.

I'm pretty sure Echo Chamber wouldn't work with Horobi, once the creature is targeted it is destroyed and the ability is countered.

You're better off not using Cabal Pit, you have to sac it and then you're down a land. Better off using Desert so you don't lose much to gain a removal spell. If Urborg, Tomb of Yawgmoth is out it's simply pure valuetown. Of course it is conditional upon them attacking someone.

I don't know why you're running Darksteel Ingot in a mono-black deck. I would suggest Leaden Myr, a cheaper replacement that is less appealing for opponents to steal with things like Thada Adel, Acquisitor. Nefashu is amazing with Horobi because you can destroy up to five different creatures whenever it attacks.

Flagellum is correct, Echo Chamber's ability would be countered by Horobi's triggered ability, as it kills the creature while Echo Chamber's ability is still on the stack.

Vortexflame, because it's indestructible. A mana rock that lives through Nevinyrral's Disk, Obliterate, etc. can steal games. Leaden Myr, as much as I love him, dies to a stiff breeze, especially in EDH. I can see where the concern for stealing it comes from, though I'd sooner expect them to steal Extraplanar Lens or Sol Ring.

Shizo, Death's Storehouse, Urborg, Maze of Ith, Tower of the Magistrate, and Desert all seems like fantastic land choices.

I think Cauldron of Souls beats out most if not all of the artifacts you listed there Draw_Wurm, though some of them do seem like reasonable choices. Power Matrix in particular. Without Horobi out it gives you the option to turn the tides of a combat phase between two of your opponents in whichever way would most favor you. Handing Trample and Flying to the aggressor's most powerful creature can lay some serious hurt on the defender, whereas handing Flying and First Strike to a defender's creature could knock out the aggressor's biggest threat. Lots of political options there.

Vortexflame. Just for the indestructible over Charcoal Diamond. No other reason really!

Tyrant-Thanatos. Crossed streams!

Yeah, I liked Power Matrix and Erratic Portal along with Mimic Vat. Cauldron of Souls may still be the best shout.

Trying to work out if should make some more cuts. A lot of people suggesting Nefashu, and I'm wondering about Ob Nixilis Reignited.

Ob Nixilis Reignited is a good card. I'm iffy about his inclusion in a political deck like this. At his worst he's a pricier Phyrexian Arena that turns on a bit faster, but I'm not sure how commonly his -3 would come in handy given how easy it is for you to dispatch creatures, and his -8 is directed at a single player. If you really like him and want to use him, I'm sure you can find space, and he won't exactly drag the deck down.

Additional cuts varies on how much you want to lean on Horobi. In Garruk's Wake, for example, can be devastating, but really doesn't give a damn if you have Horobi out or not. If you were to run something like Touch of Darkness in it's place, it would be reliant on Horobi, but so much more efficient.

If you don't expect him to stick around for long though, then you may want to hang on to cards like In Garruk's Wake.

I don't know your playgroup's meta well enough to make that call though.

Oh, and one more thought, on cards to protect Horobi, Eldrazi Monument. I don't know that you'd have enough creatures to feed to it, but indestructible to your side of the board is a great way to keep Horobi from backfiring on your creatures, himself included.

Tyrant-Thanatos Hex Parasite might actually be better anti planeswalker tech with the potential to wrath.

Retribution of the Ancients and Retreat to Hagra are a couple of other Horobi dependent enchantments. Will need to do some testing!

Yeah! I'd actually meant to mention Hex Parasite earlier! Without Horobi online it's an excellent card, anti-planeswalker, anti-a-lot-of-things. With Horobi online though, it also gains ": Destroy target creature." which is nuts. Being a dinky 1/1 for 1 is a bit of a drawback, but it brings so much to the table it's hard to deny it a slot.

I'm not sure about Retreat to Hagra, but Retribution of the Ancients would be very similar to Hex Parasite, just without the anti-counters tech.

There's a lot of options and different ways you could take this idea.

Scuttlemutt is another interesting pick. Being a creature is a downside, but it's a mana rock and a Murder engine. Not amazing but can be amusing.