24 Days of New 40k Detachment Rules Revealed for Grotmas

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Every Warhammer 40k faction received a new 10th Edition rules detachments for the Grotmas Calendar, which replaced the Advent Engine in 2024.

Updated on March 20th, 2025, by Rob Baer with the latest new 40k rules FAQs and links. As well as the three newest detachments for Custodes, Orks, and Tau.

Exciting news for Warhammer 40k fans, the Grotmas Calendar took over in 2024, bringing fresh 10th Edition detachment rules for every faction. This update replaces the Advent Engine and introduces new strategies and gameplay options across the entire Warhammer universe. From the disciplined Astra Militarum to the sly Drukhari, each faction now has unique detachments that fit seamlessly with your existing armies.

A Warhammer 40k Celebration

The month-long rollout added a whole new layer of fun and variety to your battles, making your 10th Edition games even more dynamic. Time to update your army lists and for the latest Warhammer 40k action with the awesome additions from the Grotmas Calendar!

Grotmas 2024 ‘Gifts” 30 New Detachments For Warhammer 40k

Grotmas, Sanguinalia, or whatever your preferred holiday moniker may be—‘tis the season of bolters and biomass, of merry mayhem across the Warhammer universe! Games Workshop has gifted us something far more exciting than socks: a series of new detachments for every faction in Warhammer 40k (which is probably better than the canceled Advent Engine.)

Here are the last 12 days of Grotmas 2024 leading up to the Christmas Previews.

They didn’t leave Age of Sigmar out either, as Games Workshop gifted them eight new Regiments of Renown.  Plus, on the 11th day of Grotmas, GW released the updated Balance Dataslate and points changes for Warhammer 40k.

So, there is a lot to unpack, rules-wise, for Warhammer 40k, leading up to the Las Vegas Open in 2024. But the good news is all these rules will be legal for play then, so get your playtest games in now! 

March 2025 Changes & FAQs

The latest round of Warhammer 40K FAQs has landed, and there’s plenty to talk about. Three new detachments have joined the fray, but we have those rules below. Instead, let’s get into the rule tweaks that could shake things up on the battlefield.

First up, the Solar Spearhead Unstoppable Stratagem just got a serious boost. Before, it could only be used in the movement phase. Now? It’s got flexibility—trigger it in either the movement or charge phase. That extra option makes a world of difference, especially for setting up those key assaults. On top of that, the wording tweaks allow models to glide through terrain (though not enemy models), which keeps your advance smooth without awkward positioning hiccups.

The Aeldari Vectored Engines Stratagem also gets a tweak—it now lasts until the end of the turn. Subtle but effective. This means your unit keeps its repositioning trick for a little longer, adding an extra layer of maneuverability to an army already known for being slippery.

Space Marines? Good news for them, too. Adaptive Tactics can now grant Mission Tactics to an Adeptus Astartes unit that doesn’t have the ability natively. More flexibility, more ways to play.

And Orks? The Taktikal Brigade got a wording update to clarify how abilities are issued. Now, units need to pass a Leadership test to benefit from a Taktik, and failing means taking a mortal wound. Risky? Sure. But for Orks, that’s just part of the fun.

February 2025 Grotmas Changes & FAQs

For Astra Militarum, there’s a solid bonus—Valkyries now get to join in on the fun with Deep Strike abilities, just like their fellow Astra units. It’s a subtle but impactful shift, especially if you’re planning to use those air support units to hit targets behind enemy lines or keep your opponent guessing about your next move.

For Orks, the Skwad Leader errata takes a step toward more consistency by limiting the Infiltrators and Stealth abilities to Warboss Infantry models only. No more sneaky mounted Orks hiding in the shadows! If you’re running a Kommandos-heavy list, this means you’ll have to rethink how you get those nasty units into position without the benefit of stealthy movement.

World Eaters get a slight shift with the Gory Dedication ability now triggering at the end of the Fight phase instead of when the unit destroys its first model. It’s a small change but one that could throw off your timing if you’re planning to stack those kill bonuses early.

On the Imperial Knights front, if you were hoping to give your Adeptus Mechanicus units Doctrina Imperatives in a Questor Forgepact Detachment, tough luck—this is a no-go. A bit of a bummer, but it keeps the focus more on the Knights themselves.

And, finally, for Deathwatch, no, you still can’t use Mission Tactics unless you’re in the Black Spear Task Force. It’s a straightforward clarification but one that helps to reinforce the importance of sticking to your chosen detachment’s theme.

Download the FAQ 

January 2025 Grotmas Changes & FAQs

Games Workshop’s latest FAQ updates are here, and they’ve sprinkled in everything from bug fixes to subtle power tweaks. Let’s take a stroll through the changes, keeping it light and fun. You can download all the changes to your detachment here. 

Adeptus Custodes
The golden boys got a tweak to their Solar Spearhead detachment. The Veteran of the Kataphraktoi stratagem now takes place in the Command Phase, bringing some much-needed clarity. It’s a minor change but keeps things running smoothly—less time arguing, more time flexing your Custodian muscle.

Adeptus Mechanicus
AdMech players, rejoice (or chuckle at GW’s proofreading)! The Haloscreed Battle Clade and Noospheric Transference finally got the Adeptus Mechanicus keyword added. This was probably just a typo, but hey, it’s fixed now, and your battle clade is officially part of the Mechanicus family. Welcome to the fold, little typo!

Chaos Knights
For those stomping around with Chaos Knights, GW cleaned up the wording on the Conoclast Fiefdom and Dark Sacrifice rules. They added the keyword “friendly”, which is a subtle but important fix. Now you can’t trigger abilities off your opponent’s Chaos Knights in a mirror match. It’s like GW reminding you: “Play nice with your own toys, not someone else’s.”

Deathwatch
Here’s a fun one: hand flamers got the Pistol keyword added. On the surface, this is just common sense (hand flamers should be pistols, after all), but it also makes them sneakily stronger. Picture this: shooting with your hand flamers while still able to fight in combat. Yep, Deathwatch just got a bit spicier.

Necrons
The undying legions got a couple of adjustments. For starters, the Starshatter Arsenal and Reactive Reposition now read: “Your unit can make a Normal Move of up to D6″.” It’s a small wording change but clarifies things nicely. Also, Demanding Leader now happens in your Command Phase, bringing the timing in line with other similar abilities. Necrons may be ancient, but now they’re a little more in sync with modern game rules.

Thousand Sons
The Hexwarp Thrallband detachment got a tweak to the Empowered Manifestation ability. It now specifies that you can add up to 6 inches to your range. Translation? You’re no longer obligated to max out the range if you don’t want to. This is basically GW saying, “We get it, sometimes less is more.”

The Big Picture

This FAQ batch feels like a mix of quality-of-life updates and small balance tweaks. It’s like GW went through their notebook and said, “Oh, we should probably fix that.” Whether it’s adding keywords that should’ve been there from the start, tidying up phrasing, or making hand flamers that much cooler, these changes keep the game polished.

Rules For Every 40k Faction: December 1st–24th, 2024

In December 2024, Warhammer 40k got a holiday upgrade with fresh rules detachments rolling out daily for the Grotmas Calendar. Like an overloaded servitor delivering crates of promethium, the gifts come in steady bursts of creativity.

Every faction is represented, so whether your passion lies with the righteous defenders of humanity or the xenos who would burn it all down, there’s something to look forward to.

The beauty of these detachments is their design philosophy. They’re not here to overthrow your Codex setups or leave you scrambling to overhaul your army. These additions slot right in alongside existing options, ensuring compatibility for factions still waiting on their official codex book release.

Points and Practicality: Ready to Play Today

No waiting for new books or updates—these new 10th Edition 40k Grotmas Calendar detachments come with their own points and rules. It’s like getting an immediate upgrade to your army without needing to wade through datasheets and errata.

So crush your opponents in matched play; these additions are ready for action straight out of the vox-caster.

T’au Empire: Experimental Prototype Cadre

T’au firepower is already terrifying, but the Experimental Prototype Cadre detachment makes it ridiculous. Fusion Blades on a Coldstar Commander makes an elite assassin, while Supernova Launchers on Breachers let them wipe squads before they get close. Pairing Threat Assessment Analyser with Experimental Ammunition gives Crisis Suits monstrous firepower—just keep those drones handy to clean up any Hazardous mishaps.

Orks: More Dakka!

The More Dakka! detachment is all about volume. Targetin’ Squigs + Dead Shiny Shootas means more shots and more hits, while Long, Uncontrolled Bursts + Speshul Shells ensure those bullets actually do damage. Pairing Call Dat Dakka? with a unit like Lootas means your opponent gets punished for shooting at you. Orks don’t just shoot—they drown the enemy in a storm of lead.

Adeptus Custodes: Lions of the Emperor

The Lions of the Emperor make Custodes nearly unkillable and terrifying in melee. A Shield-Captain with Martial Perfection becomes a walking blender, while Unleash the Lions turns Terminators into unstoppable single-model juggernauts. Pairing Paragon of the Emperor with Sovereign Executioner makes a perfect Character-killer, and Unbreakable Will ensures that once Custodes claim an objective, they’re not leaving.

Space Wolves: Champions of Fenris

The Champions of Fenris detachment turns your Space Wolves into tactical beasts, letting infantry and walkers charge during your opponent’s turn with The Great Wolf Watches rule.

Add in bonuses like Objective Secured for Terminators and stratagems that boost lethality, resilience, and objective control, and you’ve got a recipe for chaos on the battlefield.

Black Templars: Wrathful Procession 

The Wrathful Procession Detachment for Black Templars focuses on aggressive melee tactics, leveraging Zealous Litanies to boost movement, melee strength, and survivability. Key rules include Relentless Momentum, allowing units to fight from 3″ away, and Sacred Rage, granting Fights First for devastating charges. 

World Eaters: Vessels of Wrath

The Vessels of Wrath Detachment supercharges World Eaters champions with the Wrath of Khorne rule, granting them the Vessel of Wrath keyword to activate extra Blessings of Khorne each battle round, boosting their power and their units.

Its stratagems, like Overshadowed by None and Punish the Craven, enhance melee dominance and punish cowardly foes, while Gory Dedication secures blood-soaked objectives.

Tau Empire: Auxiliary Cadre

So the new Auxiliary Cadre Warhammer 40k detachment rules are a dream for T’au players who love blending Kroot, Vespid, and Fire Caste units into a single, coordinated strike force. This detachment focuses on integrating alien auxiliaries into your army to unlock unique synergies, enhance battlefield control, and maximize tactical versatility.

Blood Angels: Angelic Inheritors

The Angelic Inheritors Detachment captures everything we love about the Blood Angels—elegant fury, heroic moments, and devastating combat prowess. This new detachment gives you the tools to strike hard, adapt quickly, and tap into the legacy of Sanguinius himself.

From soaring jump pack heroes to precise melee assassins, the Angelic Inheritors rules let you craft a force worthy of their Primarch!

Adepta Sororitas: Champions of Faith

The new Champions of Faith Warhammer 40k detachment rules for the Adepta Sororitas, er… Sisters of Battle, perfectly embody their unyielding will and righteous fury. It rewards players who can manage Miracle dice wisely and leverage the Righteous buffs to elevate their Sisters into divine warriors.

The detachment rule makes your units faster, deadlier, and more resilient, letting you tailor buffs to the situation. Imagine boosting a Celestian Sacresants squad to hold a critical objective while enhancing a Paragon Warsuit team to hit hard in melee.

Genestealer Cults: Final Day Grotmas Detachment

The new Genestealer Cults detachment is all about sacrificing your squishy Cultists to supercharge your Tyranid buddies, turning mortal wounds into deadly Hit roll buffs with Psionic Parasitism. Meanwhile, the Catalyst Aura makes your enemies’ lives harder by boosting Cultists’ accuracy when ganging up around Tyranid “bodyguards.”

Throw in explosive Enhancements, sneaky Stratagems like Resistance Tunnels, and some spicy Tyranid combos, and you’ve got a swarm synergy that’s equal parts chaos and carnage!

Leagues of Votann: Hearthband Battalion

The new Hearthband Battalion for the Leagues of Votann turns your army into an unstoppable wall of precision firepower and elite durability, rewarding careful positioning and relentless advance.

With Methodical Annihilation re-rolling hits of 1 and boosting AP for Hearthguard and leaders, combined with Stratagems like Fury of the Hearth for double shots and Materialisation Matrices for surprise Deep Strikes, this detachment thrives on adaptability and close-range domination. 

Chaos Daemons: Four Gifts for Four Gods

Let’s talk Chaos. With four new Warhammer 40k rules detachments for Grotmas—one for each of the Ruinous Powers—the Chaos Daemons are practically spoiled this holiday season. Whether you pledge your allegiance to Khorne, Nurgle, Tzeentch, or Slaanesh, there’s a themed detachment tailored to your unholy preferences.

1. Khorne’s Carnage: A blood-soaked tribute to the ultimate war god, this detachment screams aggression. It’s all about relentless charges, devastating melee, and making sure your foes understand that mercy is for the weak.
2. Nurgle’s Gifts: Rot never looked so festive. This detachment focuses on outlasting your enemies with unkillable units and pestilent abilities. Your enemies won’t know whether to shoot you or sanitize their boltguns.
3. Tzeentch’s Schemes: Mastery of sorcery is the hallmark of Tzeentch, and this detachment delivers in spades. Expect abilities that bend reality itself, making every turn a labyrinthine nightmare for your opponents.
4. Slaanesh’s Speed: For those who like to keep their enemies guessing (and their models looking fabulous), Slaanesh’s detachment emphasizes speed and precision. It’s not just about hitting hard; it’s about hitting fast, elegantly, and with maximum style points.

Astra Militarum: Bridgehead Strike

Centered on elite Astra Militarum units like Militarum Tempestus and Kasrkin, this detachment excels at coordinated deployment, focused firepower, and controlling critical objectives. It rewards aggressive playstyles that rely on timing, precision, and adaptability. Here’s how to leverage the new Astra Militarum rules effectively.

Orks: Taktikal Brigade

Focused on the Ork’s clever Taktiks abilities, devastating Stratagems, and unique Enhancements, these new Warhammer 40k Ork detachments rules for 10th Edition combine tactical depth with brutal melee and ranged efficiency. Whether you’re securing objectives, delivering surprise attacks, or adapting to battlefield changes, the Taktikal Brigade thrives in the hands of a competitive player.

Drukhari: Reaper’s Wager

The Reaper’s Wager brings Drukhari and Harlequins together in a bloody game of kill-count competition, where whoever’s “losing” gets spicy rerolls to Hit and Wound rolls. Drukhari bring their ruthless firepower and Wyches, while Harlequins add dramatic melee flair, all backed by clever enhancements like Deep Strike for ambushes or Pain token manipulation.

Aeldari: Armoured Warhost

The Aeldari Armoured Warhost brings unmatched speed and precision to the table, letting vehicles shoot after advancing and re-roll their Advance rolls thanks to Skilled Crews. With powerful tools like the Guiding Presence to boost hit rolls and Stratagems like Swift Deployment for mid-game surprises, this Detachment rewards clever commanders who love finesse. 

Chaos Space Marines: Creations of Bile

The Creations of Bile detachment cranks Chaos Space Marines into overdrive with Experimental Augmentations—think turbocharged toughness, speed boosts, and extra punchy attacks. Toss in cheeky stratagems like Delayed Mutations for mid-battle upgrades (at the cost of a little self-damage) or Diabolic Regeneration to bring back the “un-dead,” and you’ve got an army that refuses to quit.

Led by the sinister Fabius Bile, this list is all about smashing face in close combat, outlasting the opposition, and looking gloriously grotesque while doing it.

Space Marines: Librarius Conclave

The Librarius Conclave lets your Space Marine psykers shine with five game-changing psychic disciplines that you can switch between each round. From boosting movement and hitting harder to setting enemies ablaze or shrugging off attacks, this detachment is all about versatility. Add in powerful enhancements and clever stratagems, and you’ve got a brainy, fiery, and tactical powerhouse on the tabletop

Imperial Agents: Veiled Blade Elimination force

The Veiled Blade Elimination Force brings assassins together for high-stakes carnage, letting them use key abilities like Overkill and Shieldbreaker twice per battle. Each assassin gets bespoke upgrades—like melta-tipped sniper rounds or grenade-happy Culexus tweaks—that dial up their lethality. With slick stratagems like Prime Target and Blind Grenades, this detachment turns every turn into a thrilling action sequence.

Grey Knights: Warpbane Taskforce

The Grey Knights’ Warpbane Taskforce turns the battlefield into a sanctified playground, where Purifiers shine with boosted precision and devastating psychic flames. With Hallowed Ground expanding as objectives are seized, their attacks grow deadlier, and Stratagems like Sanctified Kill Zone and Fires of Covenant make Chaos regret showing up. Packed with thematic enhancements and tactical options, this detachment is pure Grey Knights: holy, deadly, and totally badass!

Imperial Knights: Questor Forgepact

The Questor Forgepact detachment brings Imperial Knights and Adeptus Mechanicus together, blending big stompy robots with tech-powered synergy. Knights heal better near Tech-Priests, while Mechanicus units shoot straighter and hit harder when fighting alongside their towering allies. Add in clever stratagems and thematic enhancements, and you’ve got a force that’s as devastating as it is lore-friendly.

Chaos Knights: Dreaded Masters

Chaos Knights are bringing the pain with new rules that let you sacrifice hapless cultists for deadly perks like [LETHAL HITS] and [SUSTAINED HITS 1], turning your Damned units into literal cannon fodder. The Dreaded Masters detachment oozes Chaos flavor, boosting synergy between your Knights and mortal thralls while letting your titanic war engines stomp across the battlefield with impunity.

Adeptus Custodes: Solar Spearhead

The Solar Spearhead detachment turns the Adeptus Custodes into a golden juggernaut of war, with rules like Auric Armour, making their vehicles nastier the more they’re damaged, and Moritoi Ancients, giving their walkers extra speed and charge power. Packed with juicy stratagems like Unstoppable for terrain-ignoring tanks and enhancements like the Adamantine Talisman to supercharge melee mayhem, this detachment is all about relentless, tactical brilliance.

Deathwatch Gets Their New Index

The Deathwatch are back and ready to party—by which we mean hunting xenos with all the tactical flair and specialized firepower they’re known for. Their updated Index brings new Kill Teams, enhanced rules, and plenty of opportunities for creative gameplay. The Black Spear Task Force remains a solid Detachment option, offering adaptability against all kinds of foes.

Necrons: Starshatter Arsenal

The Starshatter Arsenal Detachment empowers Necron armies with unmatched mobility, firepower, and objective control. Key rules include Relentless Onslaught, granting +1 to hit rolls against enemies on objectives and the Assault ability for Vehicle and Mounted weapons, while enhancements like Chrono-Impedance Fields and stratagems such as Merciless Reclamation and Unyielding Forms bolster both offense and defense.

Adeptus Mechanicus: Haloscreed Battle Clade

The Haloscreed Battle Clades take the Adeptus Mechanicus from tactical to terrifying. With Noospheric Transference, your Tech-Priests can fine-tune their units mid-battle, granting buffs like faster movement, tougher defenses, or even stealth mode. The new stratagems are dripping with Mechanicus flavor, letting you pull off clever tricks like charging out of transports, shooting while falling back, or rerolling hits and wounds for maximum carnage. 

Thousand Sons: Hexwarp Thrallband

Reality is overrated, and the Thousand Sons are here to prove it with the Hexwarp Thrallband detachment. Harnessing unchecked magic and the favor of Tzeentch, these sorcerers twist the battlefield into a stage for arcane chaos and tactical brilliance—perfect for rewriting the rules of war and reality alike! Oh yeah, and you can just get rerolls of 1’s to wound all the time, and even add 1’s to wound when you’re in the zones of magic!

Tyranids: Warrior Biofrom Onslaught

The Tyranid Warrior Bioform Onslaught is all about cranking your Warriors and Primes up to nightmare status! Simple math: more of them equals more power. They’re tougher right out of the gate, enhancements turn them into unstoppable killers, and stratagems give them the sneaky tricks to keep enemies sweating!

Dark Angels: The Lions Blade

The Lion’s Blade Task Force is, at its core, a partnership. On one side, you have the Ravenwing: bikes, speeders, and aircraft that move faster than an Eldar’s quip. These units excel at sowing chaos in enemy lines, using pinpoint speed to block retreats and corral enemies like wolves steering prey into a trap.

Death Guard: The Flyblown Host

At the core of the Flyblown Host is the Verminous Haze, a detachment rule that encapsulates the ethos of the Death Guard: resilience through rot. Plague Marines and their Infantry allies gain Scouts 5″ and Stealth, giving them surprising mobility and durability. 

The Warhammer App Update: New Year, New Options

In early January, these Grotmas calendar rules detachments will find their way into the Warhammer 40,000 App, making it easier than ever to incorporate them into your games. Consider this your post-holiday treat—a little something to look forward to after the tinsel has come down and the Tyranids have eaten all the leftovers.

Final Thoughts on 40k Grotmas Calendar 40k Rules

This December, the 40k universe is brighter, bloodier, and brimming with possibilities. The new Warhammer 40k 10th Edition Grotmas calendar rules detachments are a gift for hobbyists and gamers alike, ensuring every army gets its moment in the (grimdark) sun.

Click any of the links below to jump to see all the latest preview roadmaps on their dedicated pages.

• Warhammer: The Old World Previews & Roadmap
• Horus Heresy Previews
• Warhammer 40k Previews
• Age of Sigmar Previews

All the Latest Warhammer News & Rumors

Are you disappointed to see the Advent Engine go away in 2024? Are you more excited for Grotmas calendar and to get new Warhammer 40k 10th Edition rules detachments for every army? 

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