CD10 Core: Combat

Combat is usually a large part of role-playing games and while some games may have more or less, combat will inevitably come up sooner or later. How games approach this varies a lot with some modeling combat as a tactical simulation, a table-top tactical system or leaving it entirely in the hands of the gamemaster. With CD10 being a narratively focused system, a lot of weight is put on the Keeper to keep the tension and tempo flowing in the midst of combat. The rules are simple and easy to learn for the players, leaving the Keeper to do the heavy lifting of abjudication and making decisions on the fly. The rules are deliberately imprecise to give the Keeper and players full freedom to do what they want in combat. The are no hardcoded rules for how long you can run, no complex action economy or such.

No mastery needed

The system is designed specifically to allow the players to stay immersed in the combat, rarely having to think in terms of mechanics or numbers but just focus on what their characters are doing. You can "play to mechanics" if you want and you enjoy that kind of crunching, but a player is not required to learn the intricacies of the system to succeed. After learning a couple of basic concepts, the player should be comfortable playing their character in combat.

Numbers in battle

When you are running games or playing a combat scenario in Celenia a lot of the immersion is created by the Keeper and players. Try to strive for keeping the tempo up, the rounds short and hide as many of the numbers as possible behind narratives. There is a reason CD10 does not have a hitpoint system. We're striving for a tense, quick and narratively focused combat system. It's more immersive to say that "I've been seriously injured" than "I lost 7 hitpoints" Players are also encouraged by the mechanics to think like a person, not think about mechanics to play a game optimally.

Round Order

Combat in CD10 relies on a round-by-round structure to help make sense of the chaos of combat and organize player and NPC actions. In the game world, however, each round is somewhere between 1 and 5 seconds long, depending on what happens. There is no strict length of the rounds, though. They're as long as they need to be, but generally rarely over 3 seconds long.

The Keeper should strive to not only keep combat flowing smoothly by executing everyone's actions in swift order, but also work to pressure players to keep the pace up. If the players start discussing tactics or planning to synchronize their actions mid-combat, the Keeper should break in and force the player to take action or lose their turn. There is not time to discuss tactics once combat begins! Keep the pace up and help players stay immersed! The Keeper and players all help to make this go as smoothly as possible.

Remember, however, that the Keeper also must respect people with disabilities and neurodivergence. Don't put undue pressure on people who are not enjoying it! We're playing the game to have fun, and stressing someone out who hasn't asked for it is never to anyone's enjoyment.

It is also important to remember that while combat as a whole is segmented into distinct rounds for you as players, it is not so in the game world. Everything happens largely at once, with only fractions of seconds between player and NPC actions. Let's go over how a round is structured. Each round follows a similar order.

Round structure

  1. Each participant selects an action type. (Stressing is declared here)
  2. Participants choose targets and are divided into duel-pairs as much as possible.
  3. Combat checks are made between combat pairs. Attacker and defender is determined by the checks.
  4. Determine damage potential and perform injury saves.
  5. Repeat 4-5 until everyone has spent all their actions. Then begin a new round.

Action order

CD10 does not have an initiative stat or initiative order that players and NPCs follow in combat. In-universe, everyone takes their turn (and action) more or less at the same time, so the order of things is generally of no concern. In rare cases, order may be necessary to establish, in that case the one with the highest combat skill for the weapon they are using acts first. If two people end up with the same value, the player acts first. If they are two players, they get to decide between themselves who acts first.

Duel pairs

Duel pairing is a term used to divide combatants roughly evenly in combat. Ideally, everyone should have a single opponent, but that's obviously not always possible. The reason we do this is so that the Keeper can focus on individual acts of heroism and action in an otherwise large mess of things. What goes on in the greater battle isn't necessary something you pay attention to when you're trying not to die.

When you are running combat in CD10, try to divide the players and their opponents in duel-pairs as much as possible, or at least small groups. This allows the Keeper to process one group at a time, sometimes playing multiple rounds with one pair before moving to the next. Whatever fits the narrative, the story and tension the best. Switch pairs when the situation calls for it, but don't run more than 3-4 rounds in one group, because you may leave other groups feeling neglected. Keep the tension up!

Unreadied weapons

Someone who is not wielding their weapon must first spend an action readying it before they can attack or defend. This makes ambushes particularly dangerous. See Stress, below.

Action Hold

Sometimes when you are in a situation where you don't necessarily have to take your action immediately, you may want to act together with someone else or wait for a specific condition before acting. In many RPGs you traditionally lose your turn this round or be forced to take some action and then act upon new information the next round. CD10 allows you to take the Hold Action option, where you await the result of something else before taking your action. The one who holds their action acts before the one the one whose action they are waiting for. This could be for instance someone cowering in cover, and someone aiming a gun at their location. The one aiming the gun would be holding their action for the target to pop out, and thus take their action first.

You declare what type of action you want to hold with a condition that is required for your action to be taken, such as waiting for someone to move out of cover, or someone getting into range of you. In case the condition you are waiting for doesn't come to pass, your action is lost.

In a firefight with a couple of goons Drax has no targets when it's his turn since every single goon is ducked behind cover so he declares that he'll hold an attack action for when a specific goon pops his head up.

The Keeper notes this down and proceeds to to go through the players and NPCs until he gets to a goon that has decided to pop up and shoot at Drax's comrades. The Keeper tells Drax's player that he may take his action first. Drax does so and gets to shoot before the goon who is now coming out of cover to attack.


Should a situation arise where someone gets attacked without being aware of it, they are considered to be ambushed. An ambushed character cannot take any actions on the round they are attacked, other than a single defensive action. If they are not wielding their weapon, they must take a reflex dodge action.


Every character involved in combat has one base action, barring traits or other conditions that may add more, to take every round. Each participant declare their actions to the Keeper at the beginning of the round and the Keeper handles the NPCs actions. These declarations cannot be changed once stated. This is to simulate that mental state of planning the coming moments in your head and if something unexpected happens, you're generally not fully prepared for it. The Keeper should not disclose NPC actions to the players in advance, just noting them down on a paper or keep them in her head until the NPC's turn. Everything in a round happens more or less simultaneously, and the Keeper should strive to make this clear to the players through narrative. Just because you have handled a combat exchange between a player and their target does not mean that the second player acts after that event, but at the same time.

Four Actions

There are four actions a combatant can declare without having any specializations that give them more, and any action type can be held with a condition (see held actions above):

  • Maneuver
  • Rest
  • Attack
  • Defend


A combatant may opt to Stress in a round, allowing them to gain an additional action in the round at the cost of performing every action that round at a -3 internal modifier. Stressing is declared at the beginning of the round and the player takes their first action as usual. The second action takes place once everyone else has taken their first action.


The maneuver is an umbrella term for everything that isn't attack, defend or rest. It involves things such as moving around the battlefield, readying a weapon, carefully aiming with ranged weapons, nocking an arrow on a bow or reloading handguns etc. Short commands such as "Attack!" or "Back off!" don't count as an action, but longer sentences do. A maneuver, just like any other action, takes a single action slot in a round. If it's unclear whether a particular maneuver counts as an action or not, the Keeper has final say.


Moving around the battlefield is generally assumed to be at running pace, and a character can move approximately 10 meters (30 feet) with one movement action. Should the character want to move faster or further, they can opt to sprint instead, which is an all-out dash. In this case, they'll move 15 meters (50 feet) but gain 1 Shock because of the exertion. Shock is a debilitation value we will go over in CD10 Core: Injuries.


Carefully aiming provides the next attack on that target with a +3 internal modifier for the shot. Advanced sights and cybernetics can improve this bonus further. You cannot stress and aim in the same round.


A dodge maneuver can be taken as part of defense against ranged attacks. If you take a dodge action, you are much harder to hit and provide an additional +3 DC for someone to hit you with a ranged weapon. This is on top of the usual "dodge and weave" pattern everyone is assumed to take in ranged combat, so a total of +6 DC for an attacker.


Resting is a passive action that can only be taken if you are not being attacked. It does not mean that you have to be out of combat, but if you are attacked at all in the round, the rest action goes to waste. The rest action is generally reserved for when one has defeated one's foe and is able to take a few moments to catch one's breath and look around, or sitting relatively safely in cover to have a breather. Resting is used to recover Shock.

Rest recovery

Each rest action removes two points of Shock from your character. If you have Stressed in this round, you may not spend any actions resting.


Attacking is an action with intent to incapacitate, hurt or even kill another creature. To attack you must have a weapon ready in your hands. Declaring an attack is done by stating how one attacks, which involves the weapon you use, how you use it (shoot, slash, stab, crush etc) or even unarmed fighting such as brawling. Once you have told the Keeper how you wish to attack, the Keeper calls for an attack check, which is a skill check with the combat skill of the weapon you are using. You account for all your internal modifiers and the Keeper handles all the external modifiers such as weather, range, movement etc. In melee combat, this means that a combat check is made by the opponent as well, and the winner of that exchange becomes the attacker who hits their target. The default DC for an attack check is always 9, but can be modified by the Keeper.

Attack order

In a combat with multiple combatants, the ranged combatants act before the ranged combatants. If you're a ranged fighter who is not involved in a melee, you attack before any melee fighters. However, since everyone has chosen their action at the beginning of the round, you can't "save" someone elses action by taking out their target before they attack, since everything happens at the same time.


Taking the defend action is something you do when you expect to be overwhelmed with attacks in a round. Normally, a person has one single action to use on their turn in a round, and if that action is forced into defense by losing a combat exchange, you stand unprotected from follow-up attacks.

However, by taking the defend action pre-emptively, you are not only benefiting from increased awareness and make your combat check at an internal modifier of +3 because of this, you may also defend against any number of attacks that come your way during a round. Each subsequent attack incurs a -3 modifier, however, so at some point you simply run out of ability to defend yourself. It also means that you cannot attack in this round, as you're fully focused on defending yourself. So even if you win the combat exchange, you cannot hurt your opponent, but you are much less likely to be injured.

By taking the defend action, you may also defend yourself against ranged attacks aimed at you. If you win the combat check against a ranged attacker, you have successfully dove to some form of cover nearby before they can shoot you. This also means that unless following ranged attackers has line of sight to you, they cannot attack you. This is provided there is cover nearby. If you are in an empty, barren room with nothing to hide behind, then you must instead take the pre-emptive dodge maneuver.

Defensive maneuver

A defensive maneuver is when you are trying to do something else while under attack, for instance drink a potion, yell something to someone else or maneuver around the battlefield without getting stabbed on your way. A defensive maneuver is declared as a maneuver while in melee with an opponent and is treated like a defend action. You must win the combat check in order to successfully perform the maneuver you have chosen.

Defending against Ranged attacks

Ranged attacks can generally not be defended against. The only hope of defending against a ranged attack is that they hit an armored part, your shield or that you instead take a maneuver action to dodge pre-emptively. If you've taken a Defend action and win the combat check, you manage to dive into cover before being fired upon.

Ranged Combat

In essence, a ranged battle between two individuals involves a series of attack checks determining what hits and where. There are no "damage" dice like in most RPGs, as damage is determined by the skill check. There is no way to avoid a ranged attack so deft usage of active dodging, cover and protective armor is very important to mitigate damage.


Ranged combat is chaotic, with bullets flying everywhere. A person out in the open is likely to be riddled with bullets (or arrows!) in no time. Each combatant choses a target (in phase 1) and makes an attack check, which is a skill check for the weapon they're using. The default difficulty for shooting a person who is not moving is DC 6, but can be modified by external factors such as range, lighting, weather, movement etc or internal factors such as cybernetics, psionics or injuries. The Keeper is responsible for modifying combat difficulty, as those factors are external modifiers.


It is generally assumed that a target is actively trying to weave and dodge to make hitting them harder, so when shooting at targets that are aware they are being attacked, a base DC for a ranged attack check can be assumed to be 9.


Lethality from a ranged attack is calculated by adding the ammunition (9mm, armor-piercing arrows, 5.7mm etc) damage plus the Excess of the attack check and, if advanced combat rules are used; a range modifier, together.

Automatic weapons

Some settings have weapons capable of firing multiple attacks in a very short span of time, such as assault rifles or submachine guns. Unless the CD10 Advanced: Tactical Combat module is used, modeling an automatic attack is done by subtracting the ammunition listed in the RoF (rate of fire) table for the weapon and doubling the base damage inflicted by the weapon or ammunition (but not any Excess from the skill check), provided it hits.

Automatic fire comes with a penalty to accuracy, listed in the weapon stats as ACC. This value is to be added to the Difficulty of the shot when performing automatic fire.

If you are using the advanced ranged combat module things like range, weather, visual conditions and the sort will play a large part of combat. While this does make for more interesting combat, there's also a bit of added complexity for the Keeper.


Ranged weapons with a high rate of fire (several shots per round either automatically or semi-automatically) can be used to Suppress an opponent. Suppression is a shower of ordonance towards an enemy without really trying to hit them. The purpose of suppression is to keep them from being able to return fire, aim or move around the battlefield. A suppression is performed like a normal attack, but is performed at +6 DC. Remember, you are not actually trying to hit the opponent, you're just trying to stop them from taking useful actions. The suppression applies no matter what, but you don't actually hit your target unless you succeed the check.

An opponent under suppression not only takes all actions at +3 DC but also act last in the round due to stress from the suppression. This lasts for as long as they are suppressed.

In order for a weapon to be capable of Suppression, it has to not only be able to fire several shots within a short timespan, but the target must be keenly aware of the fact that they are being fired upon. Entirely silent weapons (such as laser weapons from Cinders of the Cataclysm) cannot be used for suppression. They do not cause enough noise, chaos and disruption to scare a target.

Slow-firing weapons

A person can still be considered Suppressed when under fire from slow-firing weapons in special situations, up to the Keeper to judge. Common situations may be where someone is under sniper fire from an unseen enemy and a single shot may be immediately fatal or when someone is under fire from several opponents at once, even if none of them individually tries to suppress the target. This can account for arrows and bolts in a medieval/fantasy setting if they come in fast enough.

Melee Combat

Melee combat is handled largely the same way as ranged combat. The attack check is the meat and potatoes of the melee combat system and is what determines what the outcome of an exchange will be. An attack check is done as soon as someone has chosen a melee attack action against someone who is in range of their weapon.


The attacker's goal is to break the opponent's guard and hit them in a spot where their armor isn't directly protecting or hit so hard that it'll cause damage even through the armor. Damage is calculated in similar way as with ranged combat. You add the damage of the weapon to the Excess of the attack. Some traits, like Strong, may apply as well which is then added on top of damage.

The person who wins the combat check between the combatants is logically enough called the Attacker. The attack check is a DC 9 skill check with the weapon skill for the weapon they're using, unless the Keeper decides any modifiers should apply to the check. The person who gets the lowest Excess of the two is the defender. They may still succeed their defensive check by rolling over DC 9, but having less Excess than the attacker, so they may use the Defensive Value of their shield or weapon, potentially deflecting the attack. See Defender next for details on that.

After emptying his submachineguns, Drax finds himself face to face with a brutish goon with a large Knife. Drax pulls out his own knife, and tries to stab the goon. The Keeper decides no modifiers apply for this check so the combatants perform their respective checks. Drax has 4 in the Brawl skill and rolls 5 for a total of 9, meaning Drax has an Excess of 0.

The goon has a Brawl skill of 4 and roll a 2. Since Drax succeeded his attack, and the goon did not, Drax hits the goon and the goon must make a physical save. In addition, since the goon failed his defense (did not beat the DC of 9), he may not use the Block Value of his weapon, nor does he have any Excess with which to reduce Drax' Lethality.

The Lethality from Drax' attack is 2 Slash Damage from the knife plus his Excess, which in this case is 0. The goon is not wearing any armor and does not get to count his Block Value, nor any Excess, as additional defense. He must therefore make a physical save against 2.


The goal of the defender is to not get injured. Their opponent won the combat check, which means they get to attack. The defenders goal is therefore to mitigate as much of the incoming damage as possible and try to turn the battle in their favor. This is done in two ways narratively but only requires one check. The first is parrying with your weapon or blocking with a shield, either completely stopping the attack or at least diverting it away from vital areas of the body.

The second is positioning yourself so that the hit takes on a piece of armor that will protect you. The defense check is made during the combat check. You don't need to roll twice. The combat check is your defense check. If you succeeded your check, but had lower Excess than your opponent, your defense is counted as the Excess of your check, plus any Block Value from weapon or shield and finally your armor.

If the defense check succeeds, it does not mean that the defender has completely diverted the attack. It can mean that, but it doesn't have to. What a successful defense means is that the defender may add their weapon's or shield's Block Value [BV] to their overall defense when calculating Lethality. In most cases, this means that Lethality will be brought lower than 1, and the attack is successfully deflected, requiring no physical save.

The goon deftly attempts to parry the incoming strike. He has a skill of 4 and rolls 6, leading to a Result of 10. The Keeper determines that there are no additional difficulties applying and the difficulty is set to 9. The goon has successfully parried the attack, at least partially, with his weapon.

Since he successfully parried, he not only gets to count his Excess (1) as extra protection, he gets to count his weapon's Block Value as well. In the case of his large Knife, it's a value of 2. His total defense is therefore 1 + 2 = 3. He is not wearing armor, so he gets to reduce the total Lethality for his save by 3. Since the attack from Drax dealt a Lethality of 2, it gets reduced to -1 and no save is necessary, since it's below 1.

Lethality from an attack

The total Lethality from an attack is calculated as follows:
Weapon Damage + Excess of combat roll + Optional trait (such as Strong)

Total defense against an attack

The total defense of a defender is calculated as follows:
Armor protection + Block Value (if the defense was successful) + Excess of combat roll + Optional trait

Total Lethality

Given the above, the total Lethality of an attack then is as follows:
Lethality from the attack - Total Defense from the defender = Total Lethality (and DC for the physical save)

To simplify, the lethality of the attack is calculated by the attacker and the defense by the defender. That way, the Keeper need only compare the two values to determine the total Lethality. However, usually the Keeper is one of the involved parties in the combat and must therefore do both the calculations for lethality or defense and the total lethality.

Disengaging and escaping

If you find yourself in combat with an opponent beyond your skills or you need to get out of combat for any other reason, you take a defensive action and if you either win the check or successfully parry (0 Lethality) you can then disengage from the opponent and run away. There are no "attacks of opportunity" in CD10. If you've not disengaged, you are still in combat, even if you're trying to run away and your opponent will most likely stab you in the back.

Grappling and locking

In combat it may sometimes be beneficial to attempt to grab someone to stop them from running or acting. A grapple is performed as an attack action in melee combat (close or lower, if advanced combat is used) and is an opposed check with Brawl (or equivalent skill). If you win the check, you have grappled the opponent. If the opponent also fails his defense, you have managed a great grip on the target. The grip is retained in following rounds and does not change, unless the grappled target manages to struggle. See escape.


A successful grapple, of any level, prevents the person from moving, but they're free to take any other action that does not involve moving, or using the grappled body part. Generally grapples happen on arms or clothes, but the Keeper is free to determine which body part has been grappled. A player may aim to grapple a particular bodypart at a disadvantage of the Keeper's discretion. If the grapple is on the weapon arm, the person may not attack with that arm.


Escaping a grapple is done in another check, but modified by the grip strength. A great grip means that that grappled target must roll against +3 DC to escape the grapple. A character can attempt to escape a grapple once per round, and both characters involved in the grapple each make a check. Grip strength can change here, provided the grappler wins and the grappled target also succeeds their check, but with less Excess. Then the grip turns into a normal grip.


One can attempt to throw a person to the ground. Like grappling, a combat action is spent to make an opposed check for Brawl (or equivalent skill). Not having grappled the person already makes it harder, and the attacker must roll at +3 DC to succeed. If the target is already grappled, they roll without bonuses or penalty to resist the throw. If the throw succeeds the target is thrown to the ground as is now considered prone.


A target that has been grappled can be locked. Provided a target is grappled, the grappler can spend a combat action to make an opposed Brawl (or equivalent skill) check. The same modifiers apply as for a throw. If successful the locked target may not take any other actions than trying to escape the lock by spending their only action. They cannot move arms nor legs, but can in most cases speak, unless it's specifically mentioned that the mouth is covered. Escaping the lock is the same as escaping a grapple. The grappler can attempt a lock even if the target is attempting escape.

Coup de grace

A person who is either incapacitated, sleeping, locked or otherwise utterly incapable of defending themselves can be killed without rolling for it. A person who is defeated, lying on the ground with a sword on their throat is such a person. Do mind however that such an action may be considered dishonorable or deplorable, depending on the situation and culture.

Damage and absorption

There are four damage types in CD10, each interacting differently with armor. They are:




Weapon damage types

For melee weapons, they usually have a listing for each damage type, depending on how you use the weapon. A sword, for instance, could have Slash for striking with the edge, Pierce for stabbing and Blunt for hitting with the pommel or quillons. Ranged weapons, whether historical, modern or futuristic, generally have only one damage type depending on the ammunition used. A bow or crossbow would generally have Blunt or Pierce depending on arrow, a pistol or rifle would generally have Blunt for regular ammunition and Pierce for armor piercing ammunition. Shotguns generally deal Slash damage and futuristic laser rifles would deal Energy damage.

Some forms of magic would also deal Energy damage if it was a physical object, but they can also deal a non-descript damage type that doesn't interact with armor at all, in which case you don't care about armor.

Armor absorption types

Armors in CD10 have one absorption value per damage type. There is no "armor class" or similar evasion value for armors in CD10 as all armor works according to absorption or "Damage reduction" as it's called. The evasion part of defense is the active Defense combat check performed by the defender. The incoming damage is reduced by the armor's value. So if you take Slash damage, you use the Slash value on the armor.

This makes certain weapons or certain attacks more effective against certain types of armor.

Weapons and armor all use the exact same set of damage types, so if your setting uses different names and different damage types, make sure they are the same for both armor and weapons. For non-magic settings or settings where magic is entirely physical, the Energy type can be discarded.

Homebrew settings

Part of the strength of CD10 is its adaptability to almost any setting. However, this comes with a caveat. CD10 is a semi-realistic non-epic system that strives for an internal consistency and feel akin to something between Blade Runner and an action movie. Epic, high-fantasy and cinematic settings like DnD or Pathfinder are not the recommended settings for using CD10 in.

This extends to designing magic weapons. Strive for never giving your weapons more than one damage type per attack. Allow the weapon to be flexible and switch damage types on the fly, rather than hitting with more than one type at once. This is partly because it grounds the system in reality, in spite of fantastical elements but also because it simplifies running the system and make it less maths heavy. More maths is bad and should be avoided in CD10. The narrative, pace and tension are key elements in CD10 and the more maths you include, the less ideal it is.

Magic items in CD10 should only marginally enhance combat characteristics and rather have more interesting and narratively potent effects.

Related Reading

Cover image: CD10 Banner by Mizomei


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