Oath of Moment: Space Marines RPG
Table of Contents
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Session Zero
We are weapons. There is the Emperor, and there is war. Nothing more.
- Sergeant Avitus of the Blood Ravens
Session Zero is the part where the players and GM work together to determine what their game will be about, and make the characters who will be a part of it.
It’s the character creation session, if you’re still lost.
Game Basics
Before we make Space Marines, we have to decide what sort of Space Marines you’re making, what kind of game you’re playing. That means choosing a campaign structure and era, as well as discussing canon.
Campaign Structure
The Campaign Structure is the framework around your game, the premise and justification for what your Space Marines are doing and who they’re doing it for. Four proposals are offered for convenience:
- Deathwatch: Marines from different Chapters work together to help the Ordo Xenos with secret missions. Personal recommendation: Deathwatch fits well for cross-Chapter play.
- Joint Ops: Space Marines in big wars, Chapter Representatives in temporary joint operations.
- Renegades: Space Marines who defect or desert—you’re disconnected from the Imperium, but still bound by duty and honour.
- Specialists: You can play a squad from the same Chapter to reduce inter-character friction.
Era
Space Marines are not static. The game is set with Firstborn marines and Primaris options without deeper Horus Heresy lore. Canon is optional; the setting supports headcanons and alternative universes. The guide suggests discussing major canon points to keeptable cool and avoid friction at the table.
Canon
Warhammer 40,000 is described as a sandbox deliberately designed to support painting your own Space Marines and smashing them with others’ miniatures. The text notes the content includes non-canonical ideas and encourages players to decide what they think is cool as a group. It lists prompts for discussion about canon topics, e.g., the Horus Heresy reveals, Rogue Trader canon, Ork technology, boltguns color, etc.
Character Creation
Character creation begins with choosing a Chapter, which strongly informs culture and Primarch, then selecting a Specialization, a Culture, a Primarch, and a Personality. Each choice creates Demands and Drives in play. The document details Culture options, a list of canonical chapters alongside non-canon options (e.g., Angels of Absolution, Blood Ravens, etc.), and the major Specialization Tracks with tiered Advancement.
Specialization Tracks include:
- Tactical
- Assault
- Devastator
- Vanguard
- Apothecary
- Techmarine
- Librarian
Other important design points include:
- Your Specialization defines a Duty, Culture defines Honour, Primarch defines Blood, and Personality defines Conscience. Each Demand has a Stat, a Goal, and Triggers. Failing a Demand reduces the corresponding Stat; achieving a Goal increases the Stat. Demands can contradict each other.
- Finishing Touches: 9 Specialization XP grants three Tier 1 advances or two Tier 1 and Tier 2 advances; 8-7-6-5 starting Values define Demands; 3 Wounds; final fields for name, pronouns, and backstory.
Gameplay
Gameplay is divided into two phases: Missions and Downtime. Core mechanics include Demands, Stat Checks, and Combat. The transition between Downtime and Mission is Briefing; Mission to Downtime is Debriefing. The overview emphasizes how combat is a catalyst for narrative decisions under resource constraints, where resources are not ammunition or fate but the Space Marine’s soul.
During Missions, objectives are Primary, Secondary, and Tertiary:
- Primary Objectives must be completed; failure reduces a Stat during Debriefing.
- Secondary objectives yield Stat increases upon completion.
- Tertiary objectives offer smaller bonuses.
Requisition uses Budgets to acquire Gear. The system uses symbols to indicate costs: Duty uses white tokens (⚪), Honour uses black tokens (⚫). Equipment categories are Armour, Primary weapons, Sidearms, Grenades, and Gear. Equipment doesn’t carry over between missions.
Carrying Capacity details quantities: 1 Armour, 1 Primary Weapon, 2 Sidearms, 4 Grenades, 3 Equipment pieces with limits; upgrades do not count toward limits; Special Ammo doesn’t count toward limits.
Relics are items likely costing > 2⚫. Blessings offer rerolls; each Blessing spent grants a reroll on the next mission die.
Before a mission, Space Marines take an Oath of Moment by choosing a Trigger; breaking it has penalties; the Oath resets after Debriefing—Oaths do not carry over between missions.
Debriefing rules specify consequences for failed Primary objectives (stat penalties) and rewards for Secondary/Tertiary objective outcomes; advancement grants XP for Specialization advancement.
Demands are a central engine: each Demand has a Stat, a Goal, and Triggers. Failure reduces the Stat; achieving a Goal increases the Stat. Conscience Trials handle moral tests, using a Conscience Stat Check to refuse actions when faced with the routine tests that Space Marines encounter.
Stat Checks are simple 2d6 checks; GM selects the Stat to roll; success is a roll less than or equal to Stat. Bonuses (positive modifiers) or Penalties adjust the effective Stat; a failed Check costs resources, not Wounds.
Combat uses a “Distribute Attack Dice” system where all attack dice are pooled into a Volley. Attacks are against a target’s Thickness and Toughness; a hit occurs when a die meets or exceeds Thickness; Wounds are tallied by Toughness; some results cause Instant Death. Morale is resolved for groups; Pinned and Broken statuses affect action, Thickness, and morale in the battlefield.
The rules include a robust Bestiary with Human Foes, Demons, T’au, Drukhari, Tyranids, Necrons, and Squat foes, each with their own statistics and weapons.
Demands
Demands describe how your Chapter’s culture and your Primarch’s Blood shape your decisions. They link to four separate stat tracks: Duty (Specialization), Honour (Culture), Blood (Primarch), Conscience (Personality). Demand triggers produce consequences for actions, and the Goals grant stat increases upon fulfillment. Conscience-related Trials test moral decisions, with specific paths such as Merciful, Hopeful, Quiet, Curious, Yearning, Thoughtful, Meek.
The section provides a long list of sample Demands and triggers for each Specialization and Primarch option, including unique bonuses, thresholds (At Ten, At Zero), and specialized effects like Wolf Sense, Feel No Pain, or various arcane abilities tied to Sanguinius, Ferrus Manus, Roboute Guilliman, and other Primarchs. The Demands cover Duty, Honour, Blood, and Conscience, with different outcomes (e.g., Bloodlines like Lion El’Jonson, Jaghatai Khan, Leman Russ, Rogal Dorn, Roboute Guilliman, Sanguinius, Vulkan).
Demands of Duty
- Tactical: Goals like holding position to allow repositioning; triggers include drawing fire for a comrade.
- Assault: Goals focus on seizing objectives at bladepoint; triggers chase and close combat when outgunned.
- Devastator: Focus on long-range fire and covering brothers; triggers to take shots and cover.
- Vanguard: Stealth and drain the foe; triggers to avoid engagement without two advantages.
- Apothecary: Focus on healing and securing the squad’s survival; triggers to tend wounded.
- Techmarine: Preserve or reclaim technology; triggers to reclaim relics.
- Librarian: End missions with no miscasts; triggers to document or counter sorcery.
Demands of Honour
- Stoic: Follow planned actions to maintain honour; triggers to guide allies.
- Refined: Return unharmed; triggers to confront enemies with caution.
- Secretive: A mission objective not told; triggers to avoid exposing vulnerabilities.
- Proud: Slay a peer opponent; triggers to meet challenges head-on.
- Dour, Sharp, Cold, Warm, Heroic, Hateful: Each with distinct goals, triggers, and effects that alter the course of a mission.
Demands of Blood
- Each Primarch is associated with unique Blood demands and triggers (Lion El’Jonson, Jaghatai Khan, Leman Russ, Rogal Dorn, Roboute Guilliman, Sanguinius, Vulcan, Ferrus Manus, etc.).
- Blood-related traits include Bonus Blanks (At Ten, At Zero), Wolf Senses, Feel No Pain, Psychic interactions, and other Blood-driven effects.
The text includes a deep dive into bloodlines such as Lion El’Jonson (Loyalty, trophy rewards), Jaghatai Khan (Jetbike cost reductions), Leman Russ (charges on the battlefield), Roboute Guilliman (codex planning), Vulkan (trial by fire), Ferrus Manus (The Riddle of Steel, bionics), Sanguinius (Blood Call, draw power from blood), Corvus Corax (Liberation through victory). Each Primarch has Goals, Triggers, and special mechanics like “At Ten” or “At Zero” states.
Specialization Tracks
Space Marines excel at warfare and can advance along specialization tracks: Tactical, Assault, Devastator, Vanguard, Apothecary, Techmarine, Librarian. The book describes the 3-tier Advancement path: Level 1 (3 XP), Level 2 (6 XP), Level 3 (9 XP); linking constraints require lower-tier advances before higher-tier advances.
- The Rubicon Primaris rule allows a transition from Firstborn Marines to Primaris content after 18 XP, granting access to Primaris-only gear.
- Detailed Tier 1, Tier 2, and Tier 3 advancements are provided for each track.
Tactical Track
- Tier 1: Rapid Reload (free action to reload non-Heavy), Maintenance Rites (ignore Hazardous when wounded), Beaten Zone, Well Aimed (natural 6 on Bolt weapon always a hit), Honour the Chapter, Stay Low (count cover twice).
- Tier 2: Death & Glory (Hazardous weapon rolls become max for opponent), Disco Infernus, Combat Load (all Primary weapons +50% reserve ammo), Bolter Discipline, Wade Through, Catching Strays.
- Tier 3: Splash Zone (adds extra dice for Melta/Plasma and Bolt weapons), Pressure Cooker, True Grit, Chaff Clearer, Armour of Contempt, etc.
Assault Track
- Tier 1: Bolt & Blade, Scythe Them Down, Terror Tactics, Slip Through, Meteor Landing, Fuel Management.
- Tier 2: Matter of Honour, Counterstrike, Single-Minded, Festooned, Sweeping Advance, Boosted Dodge.
- Tier 3: Unstoppable Force, Riposte!, True Grit, Perfect Form, Thunderstrike.
Devastator Track
- Tier 1: Scorched Earth, No Mercy, Take It Down!, Custom Ammunition, Vantage Point.
- Tier 2: No Escape, Symphony of Destruction, Target Recognition, Mobility Kill, Follow My Tracers!, Rapid Redeploy.
- Tier 3: Obliterator, Big Game Hunter, Rapid Replacement, Walking Fire.
Vanguard Track
- Tier 1: Knife To Meet You, Fighting a Shadow, On My Mark, Not a Sound, In The Back.
- Tier 2: Sentry Slip, Five Finger Discount, Come Prepared, Target Spotted, Trickstab, Kill Confirmed.
- Tier 3: He’s In The Goddamn Walls!, Step Where I Step, Man on the Inside, Walk Away, Go Time.
Apothecary Track
- Tier 1: As Your Doctor..., Swift Ministrations, Soft Spots.
- Tier 2: The Good Stuff, Third Opinion, There May Be Side Effects, Heartstopper Serum.
- Tier 3: Balanced Humours, Not Today, Hypocritical Oath.
Techmarine Track
- Tier 1: Blessed Oils, Percussive Knock, Master of Machines, Privileged Access, Xenotech Studies, Rite to Repair, Rideshare Program.
- Tier 2: Privileged Access, Xenotech Studies (Gain special access to repairs on alien tech), Rite to Repair (free Repair action in combat).
- Tier 3: The Right Tool, Machine Empathy, Respect your Elders.
Librarian Track
- Psychic Powers: Winds of the Warp, Casting, Perils of the Warp, Mastery.
- Advancements: Bibliomancy, Divination, Telepathy, Theosophamy, Mind-related powers, Biomancy, Technomancy, Geomancy, Fulmination.
- Winds of the Warp: base 1d4, increase per conditions and by mission; Perils of the Warp cause dice degradation or injury. Mastery reduces Perils by one step.
- Psychic Powers: Offense and defense spells like Divination, Telepathy, Biomancy, Telekinesis, Pyromancy, Shrouding, Mind Raid, Biomancy, Geomancy, Fulmination, etc.
- Tier 3 Mastery: Psych Scourge, The Quickening, Haste, Might of Heroes, Vortex of Doom, Psychic Storm.
Armoury
Armoury Costs: Tables list Bolt Weapons, Energy Weapons, Conventional Weapons, Explosives, Melee Weapons, Armours, Mobility Equipment, Protective Equipment, Utility Equipment, Upgrades, Electronics Equipment, Signiferous Equipment, Signums, Divinator Auspex, Stummer, Photovisor, Servo-Skull, Teleport Homer, etc. Each weapon or piece has Attack Dice, Ranges, Ammo, and Special Rules. Armour lists Mk7 Aquila, Mk6 Corvus, Mk8 Errant, Mk3 Iron, Mk7b Crewman, Mk7c Reinforced, Primaris MkX (Tacticus/Phobos/Gravis). Terminator Armour, Indomitus, Scout Armour. The table shows which items are free for which Track and which are restricted for Primaris/Non-Primaris.
- Standard Bolt Weapons: Boltgun, Bolt Pistol, Heavy Bolter, Stalker Boltgun, Storm Bolter, Siege Bolter, Bolt Rifle, Bolt Carbine, etc. Primaris weapons require a Primaris Rank.
- Energy Weapons: Plasma, Melta, Laser, Grav types with distinct profiles and special rules such as Hazardous, Piercing rules.
- Conventional Weapons: Flamers, Missiles, Vengances, Castellan Rigs, Vengor Launchers, Fragstorm, Cyclone Launchers, etc. Projectiles and explosive rules included.
- Other Equipment: Mobility gear such as Grappling Hook, Grav Chute, Grav Rig, Jump Pack; Lascutter; Combat Bike; Jetbike; Forge of Shields; Refraction Fields; Iron Halo; Storm Shield; Cameleoline Cloak; Ghostweave Cloak; and various utility/medical/power equipment.
- Chapter-Specific Equipment includes unique items like Power Knife, Hydra’s Wail, Black Sword, Holy Orb of Antioch, Visage of Death, Blood Chalice, Perdition Weapon, Raven’s Eye, Watcher in the Dark, Knight’s Arms, Manreaper, Alchem Flamer, Chem-Censer, Charnabal Pattern, Seismic Blaster, Seismic Cannon, Solarite Power Glove, Gatebreaker Bolts, Indomitan Mantle, Teeth of Mars, Gorgon’s Chain, Haywire Bolts, Shrapnel Bolts, Graviton Crusher, Misericorde, Chain-Whip, Raptor’s Talons, Oppressor’s End, Blackwing Mantle, Whisper Bolts, Drakeskin Mantle, Dragon’s Breath, Cinder Grenades, Burning Halo, Carsoran Weapon, Castigatus Shield, Banestrike Bolts, Frostblade, Fenrisian Wolf, Fur Cloak, Wolf-Tooth Charm, Knowledge Is Power, Hide It Well, Athene Scrolls, Codex Astartes, Legatine Axe, Honour Blades, Bellicos Bolt Rifle, Kontos Power Lance, Cyber-Eagle Helm, Parthinian Serpent, Wildfire Sear, Athame, Excoriator, Spite Furnace, Bolt Weapons. There are many more.
- Space Marines carry a variety of armor and upgrades; Terminator Armour details, Indomitus, Scout Armour.
- Vehicles: Rhino, Razorback, Impulsor, Predator, Repulsor. Dreadnoughts as Tombs (Armored Pods). Open-Topped vehicles have special rules; Skimmer types can fly.
- Armours details: Mk7 Aquila, Mk6 Corvus, Mk8 Errant, Mk3 Iron, Mk7b Crewman, Mk7c Reinforced, Primaris variants MkX Tacticus/Phobos/Gravis; Terminator Armour, Indomitus; Scout Armour.
Bestiary
The Bestiary introduces various threats from Human Foes (Uprising, Rabble, Agitators, Defectors, etc.), Ork Foes (Boyz, ’Ard Boyz, Nobz, Stormboyz, Nobz, Gretchin, Runtherds, Trukk, Deff Dread, Killa Kan, etc.), T’au Foes (Fire Warriors, Crisis Suits, Drones, etc.), Aeldari Foes (Guardians, Dire Avengers, Howling Banshees, Wave Serpent, Drukhari Foes like Kabalites, Scourges, Raiders; Dark Eldar weapons include Splinter Cannon, Dark Lance, etc.), Tyranid Foes (Gaunts, Genestealers, Tyranid Warriors, etc.), Necron Foes (Necron Warriors, Immortals, etc.), Amphimmaterial and Daemonic foes (Psychneuein, Crotalid, Enslavers, Bloodletters, Flesh Hounds, Horrors, Daemonettes, Furies, Chaos Dreadnought, Legions such as Rubrics, Daemon Princes, Lords of Change etc.)
The Bestiary includes many detailed stat blocks, attack dice, ranges, and weapon options. It also lists various game engine notes (e.g., “The Hivemind” approach to leadership in Tyranid units, Disruption packs, Stompy Feet, etc.).
This is a compact but complete summary of the Oath of Moment rules and options. The original document contains extensive tables and weapon stats for each unit, vehicle, and weapon type, preserving the Warhammer 40,000 flavor within a flexible, narrative rules-light framework. Enjoy building your Space Marine chapters, their gear, and the battles they wage for the Emperor.