Detachment Focus: Slaves to Darkness

In this series of articles we take a deep dive into a specific detachment for a faction, covering the faction’s rules and upgrades and talking about how to build around that faction for competitive play. In this article, we’re covering the Slaves to Darkness Detachment for the Chaos Space Marines.

The only Detachment the Chaos Space Marines currently have access to, Slaves to Darkness released with the indexes. It keys off the faction’s Dark Pacts ability and seems to reflect a Word Bearers sensibility, praying to the dark gods for additional benefit and receiving them based on which patron a unit has chosen.

Detachment Overview

Simply put, the Slaves to Darkness Detachment is one of the strongest detachments in the game. Whether you’re fighting in melee or shooting across the table, it just makes your units better across the board, improving the benefits they get from their Dark Pacts and adding some powerful Stratagems to the mix. The Detachment gives an added bonus to your units whenever they perform a Dark Pact, based on the Mark of Chaos they’ve chosen. Additionally, five of the six Stratagems available to the detachment offer an additional benefit to units with a particular Mark of Chaos.

This means that Chaos Space Marines players playing with the Slaves to Darkness Detachment will need to make decisions about which marks to take when they build their lists. These will often be obvious – most shooting units want either the Mark of Nurgle or the Mark of Chaos Undivided – but there will be opportunities for other marks, and you’ll often want to think about whether it’s worth it to double up or go too hard on one mark knowing you can’t use the same Stratagem multiple times per phase* and you’ll only have so much CP.

*except for the free Chaos Lord Stratagem, of course.

During play, you basically always want to be firing off Dark Pacts unless losing a model to a failed test would be too big a risk. Expect to fail a few tests per game, but on the whole you’re going to come out ahead on the extra damage you’re doing.

That Gobbo

Detachment Rule: Marks of Chaos

When you muster your army, each time you pick a Heretic Astartes unit to include which is not an Epic Hero and doesn’t already have one of the keywords below, you must select one of these keywords (marks) for the unit to gain. Each time a unit with one of these keywords makes a Dark Pact, it gains the associated ability until the end of the phase.

  • Chaos Undivided – Each time a model in this unit makes an attack, re-roll a Hit roll of 1.
  • Khorne – In the Fight phase, if this unit’s weapons gain the [LETHAL HITS] ability as the result of a Dark Pact, each time a model in this unit makes an attack, an unmodified Hit Roll of 5+ scores a Critical Hit.
  • Nurgle – In the Shooting phase, if this unit’s weapons gain the [SUSTAINED HITS 1] ability as the result of a Dark Pact, each time a model in this unit makes an attack, an unmodified Hit Roll of 5+ scores a Critical Hit.
  • Slaanesh – In the Fight phase, if this unit’s weapons gain the [SUSTAINED HITS 1] ability as the result of a Dark Pact, each time a model in this unit makes an attack, an unmodified Hit Roll of 5+ scores a Critical Hit.
  • Tzeentch – In the Shooting phase, if this unit’s weapons gain the [LETHAL HITS] ability as the result of a Dark Pact, each time a model in this unit makes an attack, an unmodified Hit Roll of 5+ scores a Critical Hit.

Note that, outside of Chaos Undivided, these abilities only work in their respective phases and so cannot be used to improve your shooting in Overwatch. Also, there are some restrictions – PSYKER units cannot gain the Khorne keyword, and a Character unit with the Leader ability can only join a unit if both of those units share one of the keywords in the list above. This means Abaddon can join any unit, and as an added bonus, any unit he joins will count as having all five marks and receive multiple benefits every time they make a Dark Pact.

Running this Detachment means you need to make decisions about every unit during your army during list-building, but most of the time those decisions will be pretty easy:

  • If your unit’s primary role is shooting, or it’s just not great in melee, you likely want to give it either the Nurgle or Chaos Undivided keyword. Nurgle gives you a big output boost on units like Land Raiders and Obliterators, and is great on transports and units which don’t want to be hit thanks to the Dark Obscuration Stratagem. Chaos Undivided is also solid, since being able to get full re-rolls to hit and wound with Profane Zeal can make it easier to fish for Devastating wounds on things like combi-weapons and the Forgefiend’s guns.
  • If your unit’s primary role is fighting in melee, then you’re likely considering either the Khorne, Slaanesh, or Chaos Undivided keywords. The Lethal hits are only OK for Khorne, but the value here comes from being able to use the Eternal Hate Stratagem to fight on death on a 3+. It’s a solid pick for Chosen, though the more common pick there is Chaos Undivided in order to get Profane Zeal. Slaanesh is a better pick for faster units like Possessed – the Unnatural Swiftness Stratagem lets a Slaanesh unit Advance and Charge. That’s wasted on Chosen, but on Possessed who move 9″, it’s a huge boost.Swiftblade: If you’re dead set on including something with the mark of Khorne in the army, the Master of Executions with a unit of Chosen or Legionaries is the best choice. While the Master of Executions doesn’t give out fight first like World Eaters version does, it does allow you reroll all failed hit rolls when attacking a unit below starting strength, as well as wound rolls if the unit is below half strength. Being able to fish for Lethal Hits on 5+ with full hit rerolls without a CP investment (as long as you’re swinging at something below starting strength) makes a Master of Executions led unit capable of punching up hard against high toughness units. I wouldn’t be surprised to see lists pivot towards this strategy if the Chaos Lord gets a nasty points hike.
  • For all-rounder units which can do both, the mark of Chaos Undivided is usually the play. Chosen and Chaos Terminators do well with these. We also haven’t talked as much about the Mark of Tzeentch; generally you want Sustained Hits over Lethal hits on your shooting because you’ll seldom be attacking with a massive volume of bolter shots and Lethal Hits doesn’t combo with devastating wounds on things like your Forgefiend and combi-weapons. The Skinshift Stratagem gives Tzeentch units the ability to regenerate a destroyed model, which can provide some big value. It’ll give you the best value on Terminators and Obliterators (though Obliterators are much better off with Nurgle or Undivided). The good news is that if you take Abaddon and put him with Terminators, you get all five and so you don’t have to make any tough decisions around this.

Current successful meta lists tend to mix marks across a large number of units (typically Nurgle and Undivided, with some Slaanesh), choosing the most appropriate tool for each. Lists will also split marks where it doesn’t make sense to double up – so for example it’s common to see lists with two units of Obliterators running one as Nurgle and one as Chaos Undivided, so both can make use the relevant stratagems and abilities as needed. Likewise for Forgefiends. Likewise, you may take three units of Accursed Cultists, but only mark 1-2 of them with Nurgle for protective purposes, and plan to have the others use Profane Zeal.

Generally speaking, if you take Legionaries or Possessed, the play is to give them the Mark of Slaanesh for extra hits and the ability to Advance and Charge via Unnatural Swiftness. Daemon Princes and Warp Talons also tend to want the Mark of Slaanesh for the same reason.

Credit: Robert “TheChirurgeon” Jones


The six Stratagems on offer in the detachment tend to be pretty specific and aimed toward a single mark, but what’s available is an absolutely bonkers from a power level standpoint. Profane Zeal and Dark Obscuration are two of the game’s best Stratagems, and if they were the only ones you had access to Chaos Space Marines would still be a top-tier army.

  • Infernal Rites (Battle Tactic, 2 CP) – Use in your Opponent’s Shooting phase or Fight phase, after an enemy unit picks its targets. One Heretic Astartes unit targeted by said attacks can worsen the AP of incoming attacks by 1 for the rest of the phase. Basically a more expensive Armour of Contempt. Costing 2 CP basically makes this the only stratagem in the bunch you won’t use, though in a pinch you can use a Chaos Lord’s Lord of Chaos ability to make it free once per battle round as it is a battle tactic. That means giving up using Profane Zeal however, so you’ll want to save this for situations where you’re going second and didn’t already use Profane Zeal and need to protect a unit to get to the next battle round.
  • Profane Zeal (Battle Tactic, 1 CP) – Use in your Shooting or Fight phase on a unit which hasn’t fought or shot yet. Until the end of the phase, that unit can re-roll hit rolls and wound rolls of 1. If the unit is Chaos Undivided, it instead re-rolls all hit and wound rolls instead. This is incredibly, wonderfully good. It’s so good you will build half of your army around it. Combining full re-rolls to hit with the ability to proc Sustained Hits or Devastating Wounds lets you fish for fantastic results, pushing through obscene amounts of damage. The consistency alone is great. This is fantastic on Chosen, Terminators, Obliterators, Accursed Cultists, and Forgefiends. It’s the reason you take Undivided Chosen with a Chaos Lord, who can then once per battle round get you a free extra use of Profane Zeal to turn a unit of five Chosen into a real nasty threat.
  • Eternal Hate (Strategic Ploy, 1 CP) – Use in the Fight phase after an enemy unit picks its targets and pick a unit they targeted. Until the end of the phase each time a model in that unit is destroyed, roll one D6 and add 1 if the unit is a Khorne unit. On a 4+, the model can fight after the attacking model’s unit has finished making its attacks, then it’s removed from play. This is a good way of making your opponent regret charging a key unit, stabbing back at them with some nasty hits before you go. Note that as models fight and not the unit, you cannot perform a Dark Pact when a model fights on death (you only pact when you select a unit, not a model – see our Ruleshammer on Pacts for more on this).
  • Skinshift (Epic Deed, 1 CP) – Use in your Command phase and pick a unit. A model in that unit regains 3 lost wounds. If that unit is a Tzeentch unit below Starting Strength, it can return a dead model (excluding character models) with full wounds remaining. This is best when it’s bringing back expensive models, so Obliterators and Terminators. Obliterators are better served with other marks however, so the times you’ll use this are basically on Abaddon’s unit of Terminators, which gain all five marks from him joining. Or a unit of Rubrics, I guess.
  • Unnatural Swiftness (Strategic Ploy, 1 CP) – Use in your Movement phase and pick a unit. Until the end of your turn, that unit can shoot and charge even if it Fell back. If that unit is a Slaanesh unit it, can also shoot and charge even if it Advanced. This is a very solid, very versatile Stratagem. It’s good on Legionary units for turning them into baby Chosen, with more versatility for doing actions and getting into combat. It’s also great on quick, pure melee units that want to get into combat quickly and which don’t really have shooting attacks – so the Possessed, Daemon Prince, Warp Talons, and Maulerfiend are all options here.
    Swiftblade: This is also a great Stratagem to use on a shooting unit without a Slaanesh mark, particularly if someone tags a dedicated shooting infantry unit that can’t rely on Big Guns Never Tire to shoot out of combat, like Obliterators. It may not come up in most games, as you’ll already likely be strapped for CP with the other excellent stratagem choices available, but it can be a nasty surprise in a pinch.
  • Dark Obscuration (Strategic Ploy, 1 CP) – Use in your opponent’s shooting phase just after they pick targets, and pick one of those targets. Until the end of the phase, your unit gains the Stealth ability. Also, if the unit is a Nurgle unit, until the end of the phase it can’t be selected as the target of a ranged attack if attacking model is more than 12″ away. The other half of the one-two punch with Profane Zeal, and a purely defensive tool, so it never really interferes with Zeal. This is why all of your transports are Mark of Nurgle and half of your shooting units – the ability to protect units taking risky moves into line of sight is massive, and it lets you do things like drop a unit of Obliterators in a forward spot, kill something close to them, then protect them from return fire unless an opponent commits to getting too close to them with some other unit.Swiftblade: Also a very handy tool to use on cultists with the Nurgle mark in matchups with lots of ignore LoS shooting. If there isn’t a more valuable target you need to protect and you’re going second, using Dark Obscuration means the unit can guarantee it can make an objective sticky instead of being shot off the board before you get the chance.
    Rob: Very true. If I go first and can shoot a unit of Cultists off the table with indirect fire, they’re my first option – killing them means the CSM player has to dedicate another, better unit to sitting on that objective and screening. it’s like killing two units for the price of one.

Credit: Swiftblade


The Slaves to Darkness Enhancements just kind of don’t matter. There are five – one for each mark – and they vary in points, but ultimately your mark is dictated by other factors. They also all cost a little too much.

  • Talisman of Burning Blood (20 points) – Khorne model only. Add 1 to the Attacks and Strength characteristics of the bearer’s melee weapons. Each time the unit makes a Dark Pact, they get +D3 to each of those instead. This is cute, but there’s no real reason for you to take a Khorne character. The Master of Executions is probably the best target for this, but before you bring up the World Eaters version, note that getting +D3 Strength is not nearly as good as +D3 damage. It’s a fun bonus to work with, but just not something you’re going to take.
  • Eye of Tzeentch (30 points) – Tzeentch model only. Each time the bearer’s unit makes a Dark Pact, take a Leadership test for the bearer and if you pass you get 1 CP. This is a pretty solid way to get extra CP, but it’s hard to justify giving an entire unit the Mark of Tzeentch to get it.
  • Orbs of Unlife (25 points) – Nurgle model only. At the end of each Fight phase, roll one D6 for every enemy unit within 6″ of the bearer, adding 1 if the bearer’s unit made a Dark Pact that phase. On a 4+, that enemy unit suffers D3 mortal wounds. This is a cute little way to turn your character into a Death Guard Chaos Lord, and those are pretty solid. That said, your infantry unit characters don’t always have the Mark of Nurgle, If you have the extra points this could be solid on a Dark Commune.
  • Intoxicating Elixir (15 points) – Slaanesh model only. The bearer gets the Feel No Pain 5+ ability. Each time the bearer fights if their unit made a Dark Pact this phase, then after the bearer finishes their attacks one enemy unit hit by them has to take a Battle-shock test. The Battle-shock test is whatever but the 5+ FNP is basically the equivalent to giving your character 50% more wounds. If you’re taking a Daemon Prince with the Mark of Slaanesh and have 15 extra points, slam this on them to improve their longevity.
  • Liber Hereticus (40 points) – Chaos Undivided model only. Each time the bearer’s unit makes a Dark Pact, they gain both the LETHAL HITS and SUSTAINED HITS 1 abilities instead of just one. The only undivided enhancement is also the most expensive, costing nearly as much as a unit of Cultists and more than a unit of Nurglings, so you won’t ever use it. That said, it’s a fun little bonus to have, though I think you’d rather have the extra unit pretty much always.

Credit: Robert “TheChirurgeon” Jones

Playing This Detachment

As I’ve mentioned above, the general idea here is to pick the marks that best benefit each unit in your army and just always unload with a Dark Pact unless doing so would otherwise be too dangerous. You’ll often find yourself firing off Obscuration in the first couple of rounds in your opponent’s turn, and a Profane Zeal or two in your turn. The good news about Pact bonuses based on marks is that they don’t require a ton of additional strategy; you’ll almost certainly be simplifying your choices by picking the thing your mark gives you a bonus for, and that means fewer choices, generally.

Courtney Thomson’s List

We’ve already covered some of the more standard lists in the Faction Focus article for Chaos Space Marines – find that here – so here I’m going to showcase something less traditional but still successful. Courtney took this list to a 3rd place finish at the Fight Before Christmas GT in December, 2023.

Courtney's List - click to expand

Terminator Painting Motivation (2000 points)

Chaos Space Marines
Strike Force (2000 points)
Slaves to Darkness


Abaddon the Despoiler (310 points)
• Warlord
• 1x Drach’nyen
1x Talon of Horus

Cypher (105 points)
• 1x Close combat weapon
1x Cypher’s bolt pistol
1x Cypher’s plasma pistol

Dark Commune (55 points)
• Mark of Chaos: Nurgle
• 1x Cult Demagogue
• 1x Autopistol
1x Commune stave
• 1x Mindwitch
• 1x Close combat weapon
1x Warp Curse
• 1x Iconarch
• 1x Autopistol
1x Chaos Icon
1x Close combat weapon
• 2x Blessed Blade
• 2x Commune blade

Heretic Astartes Daemon Prince with Wings (210 points)
• Mark of Chaos: Slaanesh
• 1x Hellforged weapons
1x Infernal cannon
• Enhancement: Intoxicating Elixir

Sorcerer in Terminator Armour (90 points)
• Mark of Chaos: Slaanesh
• 1x Chaos Familiar
1x Combi-bolter
1x Force weapon
1x Infernal Gaze


Cultist Mob (55 points)
• Mark of Chaos: Nurgle
• 1x Cultist Champion
• 1x Bolt pistol
1x Brutal assault weapon
• 9x Chaos Cultist
• 9x Close combat weapon
6x Cultist firearm
1x Cultist grenade launcher
1x Flamer
1x Heavy stubber


Accursed Cultists (190 points)
• Mark of Chaos: Nurgle
• 10x Mutant
• 10x Blasphemous appendages
• 6x Torment
• 6x Hideous mutations

Chaos Land Raider (240 points)
• Mark of Chaos: Nurgle
• 1x Armoured tracks
1x Combi-weapon
1x Havoc launcher
2x Soulshatter lascannon
1x Twin heavy bolter

Chaos Terminator Squad (390 points)
• Mark of Chaos: Chaos Undivided
• 1x Terminator Champion
• 1x Accursed weapon
1x Combi-weapon
• 9x Chaos Terminator
• 3x Accursed weapon
2x Chainfist
7x Combi-weapon
4x Power fist
2x Reaper autocannon

Chaos Terminator Squad (195 points)
• Mark of Chaos: Slaanesh
• 1x Terminator Champion
• 1x Accursed weapon
1x Combi-bolter
• 4x Chaos Terminator
• 4x Accursed weapon
4x Combi-bolter


Nurglings (35 points)
• 3x Nurgling Swarm
• 3x Diseased claws and teeth

Nurglings (35 points)
• 3x Nurgling Swarm
• 3x Diseased claws and teeth

The Changeling (90 points)
• 1x Infernal Flames
1x The Trickster’s Staff

Courtney’s motivation for the list is to paint lots of Terminators and so it’s a bit outdated in terms of tech, but it’s still a very solid list. The big unit of Terminators has the Mark of Chaos Undivided, but they’ll be joined by Abaddon most of the time so that’s less important. The other unit is more likely to travel in that Land Raider – the Land Raider has the Mark of Nurgle so it can rock Sustained Hits 5+ (and get full re-rolls to hit if it’s near Abaddon), and it can use Dark Obscuration to avoid taking fire and getting popped before it can deliver its terminators.

The Terminators inside (a unit of 5) have the Mark of Slaanesh, which lets them disembark, Advance, and Charge in the same turn if they need to (though note they can’t Advance after disembarking if the Land Raider moved first), and that combos well with the Sorcerer’s ability to re-roll Advance and Charge rolls via Warptime for some long-distance shenanigans. They also benefit from picking up extra hits via Sustained Hits on 5+ in melee, and that combos with the Sorcerer dropping Death Hex on their target – AP-3 accursed weapons are pretty nasty!

The Winged Daemon Prince is also on the Mark of Slaanesh, giving him some very solid threat range, plus Intoxicating Elixir makes him a bit more durable.

Final Thoughts

This is just a very good Detachment; it makes all of your units better in ways that are helpful to them and also gives you some very good Stratagems to work with. It’s a major part of why Chaos Space Marines are among the game’s two best factions right now and it’s a super fun and flavorful way to build the army and play, though ideally they’d find a way to balance Khorne and Tzeentch a little bit more. That said, the army doesn’t need the other marks to be any better right now.

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