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Skip Navigation LinksHack Guidelines>Dice Pools

Dice and Dice Pools

Dice pools are formed by combining trait dice, thus to understand dice pools it is first necessary to have a basic understanding of what traits are.

In Cortex Prime most types of character abilities, called traits, are defined in terms of different steps of polyhedral dice; specifically d4, d6, d8, d10, and d12. The more sides on the die used to measure a trait, the better the trait is; bigger is better. Thus a character with Strength: d12 is objectively stronger than a character with Strength: d10.

When looking at characters, if something has a label and die rating, it is a trait. Some traits, such as Running or Ranged, are standardized, have a formal definition of what they mean and can be used for, and are fully integrated with the game system. However, it is also permitted to make up arbitrary traits such as "Sleuthing: d6" or "Rocketeering: d8", as long as a common understanding of what the trait can be used for is reached and the GM agrees to allow it.

Full character write ups are essentially a collection of sets of traits; Distinctions are a set of traits, Aptitudes are a set of traits, each Ability Set is a set of traits...even Tier or an Asset is a "set of traits" that only has one trait in it.

When a character needs to make a roll for an action or reaction, their dice pool is formed by selecting up to one (1) relevant trait die from each of that character's trait sets and collecting them together. Additionally, it is sometimes possible to include other dice such as any relevant Complications or Stress a target is suffering from, or relevant Scene Distinctions.

Forming Dice Pools

Here's a list of traits you can normally add to your dice pools using this hack:

  • Tier die
  • Up to one Aptitude die
  • Up to one Distinction die (d8 or d4)
  • Up to one Ability trait die from each of your Ability Sets
  • Up to one of your target's Stress or Complication dice
  • Up to two Asset dice

SFX and Plot Points spending allows a character to situationally include more dice in a given dice pool.

Once a dice pool is formed all of the dice in the pool are rolled together, up to two dice are chosen and added together to determine the character's total, and a third die is selected as the character's effect (which will be applied if the character's roll is successful).

However, 1's are bad. Any die that rolls a 1 is set aside and cannot be included in a character's total or used for a character's effect. Further, each die that rolled a 1 is called an opportunity. When a 1 is rolled by a player the GM may give the player a Plot Point to add a die to the doom pool. When a 1 is rolled by the GM the players may gain a benefit either because they have a SFX or Limit that requires an opportunity to be offered as part of their description, or by spending a Plot Point.

NOTE: Cortex Prime refers to this concept as a hitch if a player rolls a 1 and an opportunity if a GM controlled character rolls a 1, though it clarifies that there is no mechanical difference. This hack prefers to continue to refer to 1's as opportunities whether a player character or GM controlled character rolled it, as was done in Cortex Plus.

A die that rolled a 1 cannot be used as an effect die. Otherwise it does not matter what number was rolled on the effect die, only the step of the die matters, and determines the level of effect. A d4 effect die is pretty weak while a d12 effect die is very strong.

A character may spend Plot Points and a GM might spend dice from the doom pool to bend this standard dice pool mechanic by adding more than one die to the dice pool from a given trait set or by including more than two dice to determine the total or to include more than one effect die. Additionally, other abilities such as SFX may modify the forming of a dice pool or determination of the total or determination of the effect.

Critical Success

For every five (5) points a total exceeds the opposing total the winner can step up an effect die; for purposes of Stress and Complications stepping a d12 effect die up will Stress Out the target.

Adding, Removing, Doubling, Stepping, Moving, Borrowing

Sometimes SFX or potentially other circumstances might manipulate one or more trait dice when forming a dice pool. Such dice pool manipulation is a distinctive feature of the game system, with players (and the GM) physically engaging with individual dice which each represent some aspect of a character or the situation they are in as they form each dice pool. The language used to describe doing this can seem a little opaque (what does it mean to "step" a die?), but the concepts are quite simple and once understood very intuitive.

A trait die can be added to a dice pool before rolling; when this is indicated one of the physical dice of the correct kind is simply added to the dice pool. Thus if directed to add a d6 to your dice pool, you grab a spare d6 and put it with the pile of other dice you are forming your dice pool with.

A trait die can be removed from a dice pool either before or after rolling; when this is indicated one of the physical dice of the correct kind is simply taken out of the dice pool and set aside; removed dice cannot be used as part of the character's current action or reaction resolution. Thus if directed to remove a d8, you pick up a d8 from your dice pool and put it away from the other dice in your dice pool.

If directed to remove dice after you have rolled, instead of tossing the removed dice wherever you keep your unused dice, it is best to instead carefully place the dice being removed with their rolled side up, away from the result of your rolled dice but still in the active area of table space where the roll is being resolved; this can help alleviate confusion or disagreement during the course of resolving the roll. If directed to remove the highest rolling die from your result, then after you have rolled you take the die with the highest rolled value and set it aside (if there are ties, you may choose which die to remove). If directed to remove all 1's, after you have rolled pick up any 1's and set them aside.

A trait die can step up to the next higher die or step down to the next lower die. Thus if directed to step up a d6 remove a d6 from the dice pool and replace it with a d8. If directed to step down a d6, remove a d6 from the dice pool and replace it with a d4.

If a d4 would be stepped down, it is instead removed. If a d12 in a dice pool would be stepped up instead step up the next lower die in the dice pool. If all dice that remain in your dice pool are d12's, add a d6 to your dice pool.

A trait die can be doubled; when this is indicated a second die of the same kind is added to the dice pool. Thus if a d6 were doubled a second d6 would be added to the dice pool, if a d8 were doubled a second d8 would be added.

Under some circumstances a die can be moved to or from the doom pool (the GM's dice resource). When directed to move a die to the doom pool physically take the indicated die and hand it to the GM, who will then add the die to the doom pool. When directed to move a die from the doom pool the GM will take the die from the doom pool and hand it to you. If not instructed otherwise, discard dice moved from the doom pool after resolving the dice roll.

Under some circumstances a die can be moved to or from a dice pool controlled by another player. When directed to move a die from some other dice pool, the controller of the dice pool you are moving the die from will hand you the die. When directed to move a die to some other dice pool, hand the controller of that dice pool the die and they will immediately add the die to their dice pool. If not instructed otherwise, players who received one or more dice from other players in this manner should return the dice to one another after all relevant dice rolls have been resolved.

Under some circumstances a die can be borrowed from the doom pool (the GM's dice resource). This is exactly the same as moving a die from the doom pool, except that after the dice roll the borrowed die is used for is resolved the borrowed die is returned to the doom pool.

These dice manipulations are often combined; for instance you might be directed to step down a die and then double it, or to borrow a die from the doom pool to include in a dice pool and then after resolving the roll to step the die up and return it to the doom pool. In some cases there might be multiple manipulations directed by two or more SFX. When such manipulations are called for, follow the directions of the rules text as written. If there is any conflict or confusion as to which of several manipulations should go first the acting character has priority and the player or GM responsible for that character determines the order.

The Doom Pool

In much the same way that player characters have a narrative resource in the form of Plot Points, the doom pool is the GM's narrative resource. The difference is that instead of being represented in the form of chits or tokens, it is represented by doom dice ranging in step from d6 to d12. The doom pool never has d4 dice in it; if a doom die would be stepped down to a d4 it is discarded. The doom dice in the doom pool can be used in three basic ways.

The Doom Pool As Opposition

The first way doom dice are used is as a dice pool, like any other dice pool used in this game. In some circumstances, the GM will pick up some or all of the doom dice currently in the doom pool and roll them to react to things that one or more characters are attempting. When used for this purpose, the outcome is resolved in exactly the same way as any other dice pool resolution in the game. The GM keeps a couple of dice for their total and an effect die. After the roll is resolved all of the doom dice go back to the doom pool.

In addition to the dice in the doom pool, the GM can also include any Complications, Stress dice, or Scene Distinctions that would interfere with the player characters succeeding, but if they do the relevant dice should be kept distinct from the doom dice so that they are not accidentally put into the doom pool with the other doom dice after the roll is resolved.

What circumstances call for the doom pool to be used in this way? When the player characters want to try something that's important enough to break out the dice for and no NPC is directly opposing them the result of the doom pool roll provides passive opposition.

Doom Dice as Plot Point Equivalent

Doom dice can also be spent by the GM for various things, in exactly the same way as Plot Points are spent. If something says a Plot Point can or must be spent, the GM may instead spend a die from their doom pool to derive the exact same benefit. For instance, a GM can spend a doom die to include an extra die in a NPC's total or to keep an extra effect die or to activate an NPC's SFX.

Spent doom dice are discarded, i.e. removed from the doom pool.

It should be noted that when using the doom pool as opposition, the GM can spend dice from the doom pool after rolling, to keep more dice as effects or include more dice in the total, and so forth. This can get a little confusing, but it is permitted.

Doom Dice as Narrative Control

In many roleplaying games the GM (or equivalent) implicitly or explicitly has full narrative control. However in Cortex both the players and the GM share narrative control, but are each restricted by the necessity to expend some resource to exert that control in specific allowed ways. For players that resource is Plot Points and for the GM the resource is both Plot Points (for major characters they control) and dice from their doom pool. Thus, in addition to the various functions of the doom pool that have already been described, the GM is also able to spend dice from their doom pool to assert control over the emerging narrative in a few ways.

Add a Scene Distinction

When the GM sets up a new Scene or after it has begun they can stipulate up to three (3) Distinctions for the Scene for free. Scene Distinctions are just like player character Distinctions, except they describe the general environment or situational considerations governing the Scene. For instance, a warehouse on the docks might have Distinctions such as Vermin Infested; Dank, Dark, and Dilapidated; and Full of Large Boxes. Characters in the Scene can situationally use these Distinctions when forming dice pools; if a Scene Distinction is somehow helping them out they could add a d8 and if it were somehow hindering them they could take a d4 and receive a Plot Point after the roll is resolved.

At any time, the GM can add more Scene Distinctions by spending dice from the doom pool; each additional Scene Distinction costs a die of any size from the doom pool. Usually this should be in response to something happening in the emerging narrative and thus be self explanatory, but the GM should be able to explain why they are adding a new Scene Distinction and what it is meant to represent if questioned by a player.

Add an Asset to a NPC

The GM can spend a die from their doom pool to give a GM controlled character already in play an Asset of equal step, as it makes sense to the emerging narrative. For instance, the GM could spend a d6 to suddenly reveal one of their characters have a Concealed Pistol: d6 Asset. If one of the player characters had recently given that character a thorough search for weapons this would not make sense to the narrative and the GM should not do it, otherwise...fair game.

Splitting the Party

The GM can spend one (1) d12 from their doom pool to start an additional Scene and split the group of player characters in the current Scene, such that at least one player character remains in the current Scene and at least one player character is now part of the new Scene.

This may sound odd when explained in that way, but it is pretty intuitive in practice. Imagine a group of adventurers is advancing down a dungeon hallway when a trap door opens and one or more of them slalom away via a chute to some other part of the dungeon. Or a pulp era group of heroes who are desperately trying to find a criminal at a busy train station when one of the trains departs with one of them aboard separating them from their allies...and of course the villain is on the train too! Or a handful of beleaguered investigators are tromping through a Lovecraftian swamp to root out a coven of cultists before they can complete their nefarious ritual, only for a faceless nightgaunt to swoop down and snatch one of the investigators before flying off with them into the mist enshrouded night.

To be clear, a party of player characters may split up by other means, which does not cost the GM anything. This option simply allows the GM to assert such an outcome, narrating what occurs. The typical form is to pause the ongoing Scene, narrate what is happening to split the group, set up the parameters of the new Scene, and then ask the players what they do next.

End an Action Scene

The GM can spend two (2) d12 from their doom pool to arbitrarily end an Action Scene, and narrate the outcome. If the player characters are doing well and the GM simply wants to wind up the Scene for pacing reasons, the GM should allow the players to narrate how the Scene ends or work out a compromise with them. If the player characters are not doing well, the GM may ask the players to describe how they failed and what the consequences of that are, or may opt to narrate a disfavorable outcome of their own devising.

This provides the GM with a powerful pacing mechanic and can help cut short interminable combats or other time wasters, or as a goad to put players on a clock to wind up a Scene on their own...the players should notice when the GM is building up to 2d12 in their doom pool and take the hint to wrap things up before the GM forces the issue. It also provides the GM with a powerful plotting mechanic as they can use the opportunity to force circumstances that occur in scripted fiction quite often but which players generally resist or avoid, such as player characters being captured, or villains escaping, or MacGuffins getting stolen. However, there are limits to how far the GM should take this...while it is viable to narrate an outcome that results in the player characters being captured, it would generally not be ok to have them maimed or violated or otherwise undermined in a way that oversteps social boundaries.

When the GM exercises this option, all the player characters in the Scene receive one (1) additional Advance at the end of the session.

Extended Options

Other game abilities may offer the GM additional options to spend dice from their doom pool when they are in play. For instance some Limits or Milestone Goals may specify an option for the GM to spend a die for a specific outcome. All such abilities describe when and how they interact with the doom pool.

Growing the Doom Pool

Under normal circumstances the GM starts each Story with 2d6 in their doom pool, but heightened circumstances will sometimes indicate more dice or dice of a higher step (d8 or d10), or both. The dice in the doom pool will expand and contract over the course of play. Any dice remaining in the doom pool when a Story has ended are lost, so the GM is motivated to use up the doom pool if they can as a Story comes to close.

Usually the GM will narrate some description for what is going on in the Scene related to the situation which caused the doom pool to grow but in the case of activating an opportunity offered by a player character it is also acceptable for the player who offered the opportunity to explain how what they've just done has made the situation worse for the players, if the GM approves. This can add a lot of color and fun to the proceedings.

Activating player opportunities is the primary way the doom pool grows as play progresses. Each time the GM gives a player a Plot Point for rolling a 1 (or whatever else they did which offered the GM an opportunity), the GM can add a new d6 to the doom pool.

It is even better for the GM when more than one opportunity is offered by a player in a single roll; for each additional opportunity offered the GM can step up that d6 before adding it to the doom pool. Thus if a player rolled three 1's in the same roll, the GM could give them one Plot Point and add a d10 to the doom pool (the d6 stepped up twice). Similarly, when activating multiple opportunities the GM can opt to hand out one Plot Point per and add a D6 to the doom pool for each.

It should be noted that activating an opportunity is a choice and in some circumstances the GM may choose to not do so...for instance they may want to keep the player characters deprived of Plot Points for a while to increase tension. However, the game works best when Plot Points and doom pool dice are flowing back and forth and it is usually in everyone's best interests for the GM to be generous about activating opportunities.

Aside from activating player opportunities the GM has a few more ways to grow the doom pool. The GM also has the option to apply an effect die from the action or reaction of an NPC to add the effect die directly to the doom pool; for instance an NPC could take an action which raises the dramatic stakes or sows general chaos, such as dangling a hostage off a bridge or shouting "FIRE!" in a crowded space. Also, some NPC's have SFX that directly add to the doom pool...the players will typically want to deal with such NPC's quickly!

Players can also add dice to the doom pool under certain circumstances, via some SFX, Limits, and Milestone Goals. Similarly, some SFX and Milestone Goals allow the removal of a die from the doom pool. All such abilities describe when and how they affect the doom pool.

Stepping up the Doom Pool

In addition to adding dice to the doom pool, whenever the GM could add a new die to the doom pool they can instead opt to step up a die of equal step that is already in the doom pool. For instance, if the GM were able to add a d8 to the doom pool they could instead step up a d8 already in the doom pool to a d10.