The Grand Grotmas Calendar Unveiling: Days 1–22

While the content will initially be available as downloadable files, Games Workshop plans to incorporate all new detachments into the Warhammer 40,000 App by early January.

The announcement also teased similar holiday content planned for Warhammer Age of Sigmar, with details to be revealed soon.

Here’s the complete list of free Warhammer 40,000 detachments:

01 Dec 24: Grotmas Calendar Day 1 – Grandfather Nurgle brings gifts

Like Father Christmas, Grandfather Nurgle has brought a new Detachment for the Death Guard to kick off the Grotmas Calendar. The Flyblown Host takes advantage of the diseased flies that follow in the wake of Mortarion’s forces.

Here’s the Warhammer 40,000 Design Studio with more:

As the Death Guard stride inexorably towards their foes, the battlefield buzzes with the wingbeats of a trillion swollen flies. Bloated and mutated Plague Marines march beneath a pathogenic haze, striding forward slowly and purposefully, unleashing precise salvos of diseased projectiles. The obscuring swarms foul their foes’ return fire, and whatever clots of contagion their desperate shots manage to clear away are filled moments later by yet more hovering insects. Amidst the droning miasma, the Death Guard stride on, at one with the crawling horror surrounding them. As the horrifying cloud washes over the enemy, their warriors retch and claw at their skin. The Plague Marines exploit the distraction ruthlessly, cutting down their stricken foes and leaving nothing but rotting corpses in their wake.

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Death Guard Infantry benefit from Verminous Haze, allowing them to Scout at the start of the battle and making them harder to hit. The Detachment’s Enhancements and Stratagems further the narrative:

• Rejuvenating Swarm: A warrior may call on the insect horde to regain all lost wounds at the end of each phase.
• Droning Horror: Capitalizes on the cloud of flies to keep enemies distracted, bestowing tangible battlefield benefits on the Death Guard.

02 Dec 24: Grotmas Calendar Day 2 – Hark, the Dark Angels

The combined forces of the Deathwing and Ravenwing are front and centre for today’s Grotmas Calendar in a new Detachment for the Dark Angels: The Lion’s Blade.

There is no more significant duty to the Inner Circle of the Dark Angels than the pursuit and capture of the Fallen. A Lion’s Blade Task Force combines the speed and manoeuvrability of the Ravenwing with the obdurate might of the Deathwing. The bikes, aircraft, and speeders of the former thunder across the battlefield, smashing through enemy formations to place teleport homers in key positions behind the enemy lines. Then comes the Deathwing, appearing in crackling flashes of blue light to enact retribution with brutal efficiency.

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Key Rules:

• In the Lion’s Claws (Detachment Rule): Forces any unit falling back from a Ravenwing unit to take a desperate escape test.
• The Deathwing earn +2 to their Charge rolls if their target is within Engagement Range of a Ravenwing unit.

Enhancements & Stratagems emphasize this cooperation:

• Fulgus Magna Teleport Homer: A Deathwing character can return themselves and their unit to Strategic Reserves, enabling swift redeployment.
• Knights of Iron (Stratagem): Ravenwing units can move through terrain features that would normally block their approach.

03 Dec 24: Grotmas Calendar Day 3 – A festive feast with the Tyranids

Tyranid Warriors are the order of the day in the third instalment of the Grotmas Calendar – it’s the Warrior Bioform Onslaught.

None of the synapse‐beasts of the Hive Fleets are more prevalent than Tyranid Warriors. Lethal killing machines in their own right, they serve not only as instruments of destruction but as relay nodes through which the will of the Hive Mind transmits. Armed with an array of devastating weaponised biomorphs, broods of Tyranid Warriors slaughter their way through any resistance and open a path for hordes of Hormagaunts and Termagants to obliterate all remaining opposition.

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Key Highlights:

• Tyranid Warriors and Winged Tyranid Prime gain a 5+ Invulnerable Save as leaders of this force.
• Tyranid Warriors become Battleline and have increased Objective Control.
• Synaptic Tyrant (Enhancement): Allows a Neurotyrant to join a Tyranid Warriors unit, sharing its bonuses with the entire brood.
• Synaptic Amplification (Stratagem): Boosts both a Tyranid Warriors unit and an Endless Multitude unit within 6″, granting re-rolls to Wound for a crucial phase.

04 Dec 24: Grotmas Calendar Day 4 – A light dusting of… snow?

The Thousand Sons bring arcane blizzards of Warp energy to the battlefield in the Hexwarp Thrallband Detachment.

The empyric ritualists who lead these thrallbands wield magic without restraint. Directing mindless Rubricae to seize sites of power, these Sorcerers tap into a wellspring of potential, weaving obscuring rituals and lethal sorceries. As warp energies accumulate, the battlefield crackles with mutagenic power, amplifying the Sorcerers’ spells and cloaking their thralls in arcs of coruscating force. Warpflame and hellfire engulf their foes, ensuring Tzeentch claims their souls.

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Key Mechanics:

• Thousand Sons models can re-roll Wound rolls of 1 with psychic attacks if they’re on a portion of the battlefield they control. Once the Warp intensifies, they add +1 to Wound rolls for psychic attacks instead.
• Arcane Might (Enhancement): Add +1 to the Strength of Psychic weapons for the bearer’s unit, or +2 if wholly within the Flow of Magic.
• Through the Veil (Stratagem): Lets Rubric Marines arrive from Strategic Reserves as if they had Deep Strike, while Scarab Occult Terminators can appear just over 6″ from enemies if fully within the Flow of Magic.

05 Dec 24: Grotmas Calendar Day 5 – Red is the colour of the season

Become the controlling Tech-Priest with the Haloscreed Battle Clade, a new Detachment for the Adeptus Mechanicus.

Tech‐Priests often monitor their forces remotely, but those who lead battle clades push this to the extreme, overriding their thralls’ autonomy. They beam commands and strategic directives directly into cybernetically linked minds, each soldier feeling blessed by the rush of sacred data.

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This Detachment focuses on enhancing key units through the Tech-Priest’s noospheric mastery:

• Transoracular Dyad Wafers boost Kastelan Robots, letting them benefit from Noospheric Transference and the Machine Cult’s hymns.
• The Tech-Priest’s enhanced neural capacity allows them to project their consciousness to where it’s most needed, guiding the battle clade with unerring precision.

06 Dec 24: Grotmas Calendar Day 6 – Dreaming of a silver Grotmas

The Necrons have opened their vaults for Grotmas, unleashing the Starshatter Arsenal.

Vast mechanical treasures fill the dynastic armouries. Some Necron nobles prefer swift war barques and aerial skimmers to outrun and outflank their foes, while others deploy regiments of mechanical behemoths and reanimated warriors. In either case, cosmic firepower is the name of the game.

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Starshatter Arsenal unleashes a Relentless Onslaught:

• +1 to Hit when shooting at enemy units on objectives.
• Necron Vehicles and Mounted models have their ranged weapons gain Assault.
• Chrono-Impedance Fields (Enhancement): Cloaks vehicles in time-distorting tech.
• Chronoshift (Stratagem): Automatically Advances a vehicle 6″, showcasing the Necrons’ temporal manipulation.

07 Dec 24: Grotmas Calendar Day 7 – Whether you’ve been naughty or nice, the Deathwatch are coming

The festive season is about coming together—so it’s fitting that the Deathwatch, made of diverse Chapters, has a Black Spear Task Force Index.

From hidden orbital fortresses, the Deathwatch deploy specialized kill teams to handle xenos threats. Each member is a decorated veteran on loan from their parent Chapter, sworn to the Long Vigil.

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Black Spear Task Force returns, updated for the new edition:

• Mission Tactics (Detachment Rule): Adapt to any foe—massed infantry, war engines, or elite targets—by shifting tactics.
• Site-to-site Teleportation (Stratagem): Makes Deathwatch among the most mobile Astartes, allowing rapid repositioning.
• Specialist Ammunition is now more widely accessible.
• Revamped Kill Teams:
  • Fortis (Tacticus variants)
  • Indomitor (Gravis variants)
  • Spectrus (Phobos variants)
  • NEW Talonstrike (Jump Pack variants)

08 Dec 24: Grotmas Calendar Day 8 – Gifts of gold and… death

The Emperor provides a double dose of Detachments today: the Adeptus Custodes and the Officio Assassinorum. We focus on the mighty Solar Spearhead for the Custodes.

Deep in the Imperial Palace, ancient Custodes vehicles lie dormant. Enormous auramite-clad walkers and venerable Land Raiders awaken, rumbling forth in unstoppable gold columns. Their arcane armaments unleash torrents of firepower, scouring enemies from existence.

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Key Highlights:

• Auric Armour: Grants vehicle-specific rules based on damage.
• Moritoi Ancients (Detachment Rule): Adeptus Custodes Walker units gain +2″ Movement and +1 to Advance & Charge rolls.
• Adamantine Talisman (Enhancement): +1 to Attacks, Strength, and Damage for the bearer’s melee weapons.
• Unstoppable (Stratagem): Lets a Custodes Vehicle or Mounted unit move through models and terrain, unstoppable indeed.

09 Dec 24: Grotmas Calendar Day 9 – Silent Knights, unholy Knights

We return to one of the classic Grotmas themes: giant machines battling it out. Two Detachments take the field:

Iconoclast Fiefdom (Chaos Knights)

Fallen Nobles lead hordes of heretics who worship these corrupted war engines as idols of the Dark Gods. Their deaths fuel the Knights’ Thrones Mechanicum with infernal power.

• Wretched Thralls Rule: Add Damned units from Codex: Chaos Space Marines to your Chaos Knights force.
• Dreaded Masters (Detachment Rule): Knights can perform a Dark Sacrifice while shooting or fighting, trading cultist lives for unholy boons.
• Worthless Chattel (Stratagem): Ignore engaged Damned units when selecting ranged targets—perfect for letting Knights blast past their own cultists.

Questor Forgepact (Imperial Knights & Adeptus Mechanicus)

Some Knight Houses are bound to the Adeptus Mechanicus by ancient oaths, fighting side by side for the Emperor and the Omnissiah.

• Cogbound Alliance (Detachment):
  • Sacristan Pledge: Imperial Knights regain lost wounds in your Command Phase, or D3 if within 3″ of a Tech-Priest.
  • Divine Inspiration: Adeptus Mechanicus units re-roll Hit rolls of 1 for ranged attacks, and re-roll Wound rolls of 1 if within 6″ of a friendly Knight.
• Knight of the Opus Machina (Enhancement): Re-roll Hit rolls of 1 if within 6″ of AdMech allies.
• Vengeance of the Machine Cult (Stratagem): If an Imperial Knight is destroyed, the slayer is marked, granting [Lethal Hits] to AdMech units targeting them.

10 Dec 24: Grotmas Calendar Day 10 – ’Tis the season for a sanctified killzone

When you need a world purified in record time, the Warpbane Task Force of the Grey Knights arrives.

The Grey Knights deploy the Order of Purifiers for the most esoteric, Warp-tainted crises. Their holy flame and psychic might scald corruption at its root, establishing Hallowed Ground that bolsters their resolve and cleanses foes.

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Key Rules:

• Hallowed Ground spreads across the field, increasing the accuracy of Grey Knights’ attacks—especially Purifiers.
• Radiant Champion (Enhancement): Inflicts additional mortal wounds in melee while within Hallowed Ground.
• Sanctified Kill Zone (Stratagem): Allows Purifiers to re-roll Wound rolls in the consecrated zone.

11 Dec 24: Grotmas Calendar Day 11 – The pen is mightier than the power sword

Wield the devastating power of the Warp on behalf of the Emperor with the Librarius Conclave.

When the Chapter faces daemonic incursions or xenos psykers of exceptional power, a cadre of Librarians gathers to unleash disciplined Warp-fury in battle.

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Psychic Disciplines:

• Biomancy – supercharge physical prowess
• Divination – foresee and guide
• Pyromancy – unleash firestorms
• Telekinesis – hurl enemies aside, raise psychic shields
• Telepathy – cloud minds, pierce illusions

Discipline-Specific Boosts:

• Celerity (Enhancement): Advance and Charge. With Biomancy active, Fall Back and Charge as well.
• Fiery Shield (Stratagem): Improves melee defenses; with Pyromancy active, enemy weapons become Hazardous against you.

12 Dec 24: Grotmas Calendar Day 12 – The naughty list beckons

The Primogenitor’s “gifts” are front and centre in the Creations of Bile Detachment.

Fabius Bile’s augmented Chaos Space Marines embody twisted science beyond even the Emperor’s gene-craft. In battle, their mutated ferocity tears foes apart—though they risk physical collapse from rampant enhancements.

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Key Mechanics:

• Experimental Augmentations: Choose one boost for an Infantry unit—or roll randomly for two.
• Prime Subject (Enhancement): Grants a Character re-rolls to Hit and increased Damage in close combat.
• Delayed Mutations (Stratagem): Add a second or third augmentation to a unit mid-battle—at your own peril.

13 Dec 24: Grotmas Calendar Day 13 – Santa’s larger, angrier helpers

It’s a two-for-one day: the Armoured Warhost (Asuryani) and the Reaper’s Wager (Drukhari + Harlequins).

Armoured Warhost (Asuryani)

Fast grav‐tanks, walkers, and aircraft coordinate waves of withering fire. Aspect Warriors and Guardians deploy seamlessly, capitalizing on the enemy’s confusion.

• Skilled Crews: Grants the Assault ability to vehicle weapons and lets you re-roll Advance rolls.
• Guileful Strategist (Enhancement): Redeploy up to three vehicles at game start.
• Vectored Engines (Stratagem): Enables a vehicle to shoot after Falling Back.

Reaper’s Wager (Drukhari + Harlequins)

A macabre drama played out among Drukhari and Harlequins, each competing for the bloodiest, most spectacular kills.

• Callous Competition (Detachment Rule): Whichever side (Drukhari or Harlequin) kills an enemy first leads the “wager,” and the other gains re-rolls of 1 to Hit/Wound until they pull ahead.
• Webway Walker (Enhancement): Grants Deep Strike; if behind in kills, also re-rolls Charge.
• Fateful Role (Stratagem): Models fight on death on a 4+ (3+ if behind in kills).

14 Dec 24: Grotmas Calendar Day 14 – Dreaming of a green Christmas

LISSEN ‘ERE YOO ‘ORRIBLE GROTS! The Orks of the Taktikal Brigade (Blood Axes) present new kunnin’ warfare.

Blood Axes “borrow” strategies from around the galaxy, mixing sneaky infiltration with Orky aggression.

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• Lissen ‘Ere (Rule): Warbosses and Meks provide Taktiks, boosting shooting or close-combat prowess.
• Stormboyz gain Battleline, reflecting unorthodox but effective Orky cunning.
• Mek Kaptin (Enhancement): Lets a Big Mek join Flash Gitz for re-rolls to Hit.
• Ded Sneaky (Stratagem): Return Kommandos and Stormboyz to Strategic Reserves for fresh ambushes.

Also check out updated datasheets for Tankbustas and Breaka Boyz.

15 Dec 24: Grotmas Calendar Day 15 – All we want for Christmas is an orbital assault

When the Imperium needs a key objective seized at speed, the Bridgehead Strike Detachment swoops in.

Militarum Tempestus (or elite Kasrkin) lead the way, dropping via aircraft or grav‐chutes to grab vital points, holding until the bulk of the Astra Militarum arrives.

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Key Mechanisms:

• +1 to Wound on the turn they arrive from Reserves or disembark a Transport.
• Supporting units get re-rolls of 1 to Hit as a mark of their specialized training.
• Bombast-Class Vox-Array (Enhancement): A Tempestus Officer can issue the same Order to three different units.
• On My Position (Stratagem): Calls in air support on a designated location—even risking friendly forces—to devastate the foe.

16 Dec 24: Grotmas Calendar Day 16 – Have yourself a ruinous little day

It’s the season to worship your patron god—four Chaos Daemons Detachments arrive: Legion of Excess, Plague Legion, Blood Legion, and Scintillating Legion. Here we focus on Slaanesh’s:

Legion of Excess (Slaanesh Daemons)

Daemons rarely cooperate, but Slaanesh’s thirst for pain and pleasure spurs synergy. The Seductive Gambit rule demands a risky playstyle that can reap massive rewards.

• Seductive Gambit (Rule): Lose Fight First when you charge, but gain re-rolls to Hit and Wound for that combat.
• Phantasmal Longing (Stratagem): Move unhindered through terrain.
• Sensory Excruciation (Stratagem): Forces Battleshock tests across the battlefield (including your own units) within your Shadow of Chaos.

Expect healing and revival mechanics, as long as you keep Slaanesh entertained.

17 Dec 24: Grotmas Calendar Day 17 – Glad tidings to you and your Kin

Nothing says Grotmas like a warm hearth—the Hearthband of the Leagues of Votann embodies that spirit.

The Eye of the Ancestors directs the Kindred to dispatch Einhyr elites and top-tier Hearthkyn in unstoppable columns. A Hearthband sees its mission through, no matter the odds.

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Key Highlights:

• Methodical Annihilation: Re-roll Hit rolls of 1 against the nearest enemy. Units with champions gain an additional point of AP.
• Quake Multigenerator (Enhancement): Disrupts enemy movement and counterattacks.
• Superior Craftsmanship (Enhancement): +1 Damage against Monsters or Vehicles.

18 Dec 24: Grotmas Calendar Day 18 – Wish upon the Star Children

The Genestealer Cults love a countdown. Their Final Day Detachment fuses human zeal with Tyranid might.

Cultists anticipate “holy ascension” as Tyranids arrive. The Hive Mind devours most of them—but, in-game, that synergy can be lethal.

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• Psionic Parasitism (Rule):
  • Include Tyranid Vanguard with your Cult.
  • Cultists get +1 to Hit if the enemy is within 6″ of those Tyranids.
  • The Tyranids themselves gain +1 to Hit and heal Wounds using Cultist bioenergy.
• Inhuman Integration (Enhancement): Grants Sustained Hits 1 to a chosen unit’s weapons.
• Avenge the Star Children (Stratagem): If a Tyranid Character is slain, Cultists get +1 to Hit and +1 to Wound against the killer.

19 Dec 24: Grotmas Calendar Day 19 – Oh come all ye faithful

Join the choir! The Champions of Faith Detachment gathers the Adepta Sororitas’ most pious sisters.

When a critical mission arises, the Sororitas deploy their holiest warriors, each vow sworn with unwavering devotion to the God-Emperor.

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• Righteous Purpose: +1 Objective Secured for Celestian Sacresants; discard Miracle dice to make certain units Righteous, boosting bravery and combat ability.
• Mark of Devotion (Enhancement): +1 Attack for the bearer’s melee weapons, plus another +1 Attack and +1 Damage if Righteous.
• To the Heart of Heresy (Stratagem): Improves Strength in the Fight phase, and extra AP if Righteous.

20 Dec 24: Grotmas Calendar Day 20 – Eat your heart out, Gabriel

Step aside, Dark Angels—the Blood Angels unleash the Angelic Inheritors.

Sanguinius’ sons inherit his grace, psychic might, and a bitter curse that drives them to transcendent fury when all seems lost.

• Legacy of the Angel: Three boons (Fall Back/Shoot/Charge, re-roll 1s to Hit/Wound, or re-roll Advance/Charge). Blood Angels choose two for all Characters at battle start.
• Troubling Visions (Enhancement): Temporarily grants a Character all three boons for an overwhelming assault.
• Unto the Burning Skies (Stratagem): Lets Jump Pack units re-enter Strategic Reserves at the end of your opponent’s Fight phase. The Sanguinor can even do so from Engagement Range!

21 Dec 24: Grotmas Calendar Day 21 – It takes all sorts

The T’au Empire’s Grotmas feast includes the Auxiliary Cadre—Kroot, Vespid, and more.

The T’au’va encourages unity with alien species. Auxiliary Cadres take it further by fielding a majority of non-T’au aliens supported by T’au specialists.

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• Integrated Command Structure (Rule):
  • Non-Auxiliary T’au get extra AP vs. enemies within 9″ of Auxiliaries.
  • Auxiliaries can’t be targeted beyond 18″ if within 6″ of a non-Auxiliary T’au unit.
• Admired Leader (Enhancement): Improves Leadership & Objective Secured for Kroot/Vespid.
• Guided Fire (Stratagem): Boosts Strength on a non-Auxiliary unit’s ranged weapons if Kroot/Vespid are nearby.

22 Dec 24: Grotmas Calendar Day 22 – A Grotmas message of pure, unbridled hatred

Lastly, the Black Templars arrive like the least-welcome carolers imaginable. Fear the Wrathful Procession.

Experts in shock assaults with heavy infantry, the Black Templars thrive where tanks can’t. Hate-fueled orations drive them forward like a holy avalanche that shatters enemy lines.

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• Zealous Litanies: Each battle round, pick one of three prayers that buff Move, Strength, or Invulnerable Saves.
• Sacred Rage (Enhancement): Once per battle, grants Fights First to the bearer’s unit.
• Relentless Momentum (Stratagem): Attack from up to 3″ away, letting huge Crusader squads bring every weapon to bear.