Legacy Mono-Black Curses – Deck Guide

There are a wide array of decks in Legacy that take advantage of Chalice of the Void. While they tend to share a common goal, the ways each of them seek to end the game can differ quite wildly. Mono-Black Curses, a deck created and tuned by Magic Online player Reeplcheep, is a perfect example of how differently Chalice of the Void strategies can be executed. 

Reeplcheep recently Top 16’d a Magic Online Legacy Challenge with Mono-Black Curses, so this seemed like a great time to explore the archetype. This is a pretty unique deck and does a lot of really cool things, so I’m excited to take a look at it today!



Legacy Mono-Black Curses by Reeplcheep



Header - The Game Plan

This is a linear prison deck that seeks to prevent its opponents from playing the game as much as possible. To accomplish this, it uses three primary approaches: artifacts such as Chalice of the Void, Curses such as Curse of Death’s Hold and Karn, the Great Creator.

Having a diverse suite of lock pieces means that Mono-Black Curses is pretty versatile in its ability to lock an opponent out, which can make it challenging to answer. To actually win the game, it takes advantage of the powerful, yet relatively uncommon, combo of Helm of Obedience and Leyline of the Void, which tends to end the game on the spot. In addition, Cruel Reality has a tendency to end games in somewhat short order.


Header - Card Choices

Mono-Black Curses has a ton of cool and unique things going on, so let’s take a look at each card in the deck and understand what role each card plays here.


Chalice of the Void (Timeshifted)Trinisphere

The cornerstone of Legacy prison decks, these two artifacts have effectively prevented opponents from playing Magic since 2004. While Chalice’s impact has lessened over the past few months, as decks have started playing more diverse mana costs, a turn one or two Chalice still has a really good chance of stopping most opponents from playing any spells of worth. Without it, decks like this wouldn’t be nearly as effective, so four copies is a must.

Trinisphere doesn’t always see play in larger numbers in Legacy, but there aren’t many cards that have quite the impact on board as it does. Part of the reason it doesn’t see widespread play is that it’s a bit more challenging to cast on turn one, as it requires more than just an Ancient Tomb. In addition, some decks can turn its effect against you by using mana denial to prevent you from casting your spells.

However, it fits in perfectly here for a few reasons. Being castable off of Dark Ritual (more on that card later) gives Mono-Black Curses a clean path to casting it on turn one. In addition, not only do most of the cards in this deck cost more than two mana, a lot of them are pretty expensive, so buying yourself time to cast those cards is really important. While Trinisphere doesn’t show up all the time, in decks that can take advantage of its effect, it’s difficult to imagine a more effective card.


Karn, the Great Creator

It didn’t take long for Karn to be picked up in Legacy prison decks after its printing and he’s likely here to stay. I have said a lot about Karn in the past and most of that applies here. Most decks need to stop Karn as soon as they can, as he threatens to lock out opponents through a wide-variety of means. Mono-Black Curses has a relatively traditional suite of lock pieces in the board, but it has the added bonus of searching up a Helm of Obedience, which is quite nice.


Collective Brutality

This card has shown up in Legacy before, but it’s usually paired with reanimation effects. Here, it’s a very versatile answer to a wide-range of cards. Answering Delver of Secrets, clearing the way of Force of Wills or taking cards like Doomsday are all things Mono-Black Curses is interested in doing. The fact that it can do multiple things at once is a way to catch up on mana efficiency, which is pretty relevant here. Versatility goes a long way and it’s pretty cool to see this card show up in Legacy.


Hagra Mauling // Hagra Broodpit

This is similar to Collective Brutality, as it’s a pretty poor removal spell and a pretty poor land. However, it does do both of those things, which is exactly what this deck wants. These cards will always have a chance of showing up in decks because they’re very versatile and this is a good spot for Hagra Mauling. Worst case scenario, it can always be removed to Chrome Mox, which makes it better than any other land in that regard, which isn’t too bad.


Chrome MoxDark Ritual

Mana acceleration is much sought after in a deck like this, and these are some of the best mana accelerants in the format. Chrome Mox doesn’t need much explanation, as it is a mainstay in this style of prison deck regardless of color. Dark Ritual, on the other hand, might need some justification, as it looks like it works quite poorly with Chalice and Trinisphere

While the risk of not being able to get cast is relatively high, Dark Ritual is a major part of the reason this deck functions. Most prison decks don’t have easy access to three mana on turn one, but since Dark Ritual is so effective at doing that, it makes Trinisphere come down much earlier than other decks. It’s a lot like City of Traitors in that it doesn’t provide a lasting advantage itself, but the spell it’s casting will, so the risk of losing the mana source is worth the potential upside. In addition, since this deck does have relatively high mana cost and most of the lock pieces are going to be interacted with on turns one and two, Dark Ritual can seriously accelerate your plan and set up some absurd early turns.


Defense Grid

This card has been growing more popular out of Ancient Tomb decks as a way to combat Force of Will, and it does that extremely well. This deck is trying to resolve some very expensive spells, so it’s well worth the risk of occasionally being a dead card (which is probably not that often in Legacy).


Leyline of the Void (Timeshifted)Helm of Obedience

This is a very straightforward way to kill opponents in Legacy. While it is a two-card combo, which means that you won’t always be able to put it together, Leyline of the Void is generally a pretty effective card in Legacy. Starting the game with it in play will often influence your opponent’s ability to play the game and, while it might not have any effect at all (besides being a combo piece), it might just end the game on the spot against a deck like Dredge, which is a lot of upside. Helm of Obedience doesn’t quite have that impact and it mostly just functions as a combo piece, but you might be able to find a creature off of it if nothing else is going on, which is certainly better than nothing.


Curse of MisfortunesCruel RealityCurse of Death's HoldOverwhelming Splendor

The “Curses” part of the deck, this is how this deck differentiates itself from the other prison decks. By resolving a Curse of Misfortunes, which is both a difficult card type and mana cost to remove in Legacy, you give your opponents a one-turn window to answer it. If they don’t, one of these three enchantments will do a great job at stopping your opponent. 

Cruel Reality puts opponents in a real squeeze. It’s challenging to beat The Abyss in any game centered around creatures and if that aspect of the game doesn’t matter, it still puts a  real limit on how much longer the game will go. Overwhelming Splendor does a great job at ensuring that there are very few relevant cards that your opponent can have for the rest of the game. Curse of Death’s Hold pairs extremely well with Splendor, and will ensure that a random army of 1/1s won’t take over the game (while also being good against small creatures, in general).

This is definitely an odd way to approach a game of Legacy when compared with other options, but it’s certainly effective. Outside of Splendor, the other two can be hardcast, which isn’t unreasonable in this deck. Cards like Brazen Borrower do make them a bit less reliable than they might have been in the recent past, but Mono-Black Curses still presents a lot of really intimidating cards, so it’s easy to overwhelm opponents.


Ancient TombCity of Traitors

We’ve seen this suite of lands before and they are really the reason decks like this can exist. It’s a form of card advantage to have lands that produce more than a single mana and if you can pay the deck building costs, this will provide a substantial advantage over most other decks. Some decks we’ve covered in the past haven’t played the full suite of City of Traitors because losing the land can be really costly. However, Mono-Black Curses is really trying to exchange cards for mana as quickly as possible since resolving almost any permanent in the deck is going to be devastating.


SwampSnow-Covered Swamp

Seeing as this deck is mono black it can afford to play a lot of Swamps. There isn’t much upside to playing the Snow-Covered Swamp (there would potentially be more copies if there was a significant advantage), but some random value, such as making opposing Predicts worse or making your opponent think you have something that requires snow, doesn’t really hurt.


Urborg, Tomb of Yawgmoth

There is a downside to drawing multiple of these since they are legendary. However, occasionally making it so that Ancient Tomb doesn’t deal damage to tap for mana is a serious upside, so two copies makes sense here.


Header - The Sideboard

Helm of ObedienceEnsnaring BridgeLiquimetal CoatingMycosynth LatticeSorcerous Spyglass (Timeshifted)Tormod's CryptVault of Whispers

This is the Karn board, which I’ve talked about a fair amount in this past. There are cards that solve a wide array of circumstances, ranging from controlling the board (Ensnaring Bridge) to missing a land drop (Vault of Whispers). There’s an extra copy of Helm of Obedience here, which increases the consistency of the combo occurring and is really nice. Mycosynth Lattice is one of the headliners, as it completely locks out your opponent from anything but combat when Karn is in play.


Opposition Agent

While this has a fair amount of usage in Legacy overall, such as stopping Natural Order or Entomb, this is primarily an anti-Doomsday card, as that matchup tends to be really challenging for any deck not running countermagic.


Plague EngineerPlague Reaver

These cards help against all of the heavy creature decks of the format. Plague Engineer needs no introduction, as that card has been wiping Elves, Goblins, Merfolk, Rogues, Elementals and many more from the board since 2019. Plague Reaver is an uncommon card, though. It was printed in Commander Legends and it serves as a delayed wrath effect against any of the creature-oriented decks of Legacy. It has the distinct advantage of also serving as a massive body, which might act as a wall or a beater, depending on the situation. The downside is that it can be removed and requires a relatively steep cost of discarding two cards, but the upside is definitely there and it’s pretty neat to see it show up here.


Header - Tips and Tricks

  • Remember that Curses need to target an opponent, so Veil of Summer stops that from resolving. If you suspect they have Veil, try to wait a bit or go for a different threat.
  • Animating a Trinisphere and attacking with it using Karn removes the tax that it applies to people’s spells (including your own). This will mostly be a disadvantage, but keep in mind that you might be able to turn on a Dark Ritual if you need to accelerate towards something like a naturally drawn Cruel Reality.


Header - Sideboard Guide


Izzet Delver

Izzet Delver

Out: 1-4 Leyline of the Void, 1-2 Helm of Obedience

In: 2-4 Plague Engineer


Honestly, a lot of cards in the deck are pretty good in this matchup, so I’m hesitant to go overboard against them. I think the fact that Leyline doesn’t have much impact on their game plan makes the combo look less appealing. Plague Engineer is definitely strong here, but I’d stay away from Plague Reaver, since giving them a huge creature to attack with is part of what they want to do anyway.





Out: 2 Hagra Mauling

In: 2 Opposition Agent


Again, a fair amount of the cards seem solid in this matchup. I want to bring in Plague Engineer for cards like Monastery Mentor, but I think Curse of Death’s Hold carries enough weight there. The artifact prison pieces are excellent in this matchup and Leyline stops Uro from being a pest. I think the primary plan is pretty effective in this matchup, so I don’t think you need to over board against them.





Out: 2 Hagra Mauling, 1 Curse of Death’s Hold, 1 Overwhelming Splendor

In: 2 Opposition Agent, 2 Plague Reaver


Landing early lock pieces will help for sure, but this deck is still really tricky to play against. There just aren’t that many cards that actually stop them from comboing, and most of the prison cards just slow them down a bit. I think the best route is to try to turbo out a combo yourself.

Plague Reaver doesn’t do anything when it comes to clearing their board, but having a huge creature in play will substantially reduce the number of turns they have and that’s important here. It might be correct to bring in the Engineers as well (there certainly are more cards like Hagra Mauling to bring out), but they don’t really seem like they apply enough pressure to warrant that.



Death and Taxes

Death and Taxes

Out: 2 Defense Grid, 4 Leyline of the Void, 2 Helm of Obedience

In: 4 Plague Engineer, 2 Plague Reaver, 2 Opposition Agent


I’m willing to believe that I’m wrong, but seeing as Death and Taxes has a very clean answer to either part of the combo in Skyclave Apparition and that the graveyard hate doesn’t matter, I think the combo should come out in its entirety. Each of the cards coming in has an impact on the game in one way or another, and it seems safer to just rely on lock pieces and anti-creature measures than try to mess around with a two-card combo.

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