Dice pools may be transitory (e.g. being built for a single roll as part of a resolution mechanic) or permanent (e.g. building over the course of a game session to indicate rising tension or danger, as in Marvel Heroic Roleplaying's Doom Pool).
Building a dice pool for a resolution mechanicEdit
When a dice pool is needed for a resolution mechanic, it needs to be built according to the rules of the game at the start of resolution. Dice may be added to (or removed from) the pool based on factors such as the active character's stats, their equipment, their situation, the nature of the task being resolved, etc. For example, in Chronicles of Darkness and 7th Sea (2nd edition) players build dice pools made up of a number of d10s equal to the score of one of their character's attributes (called traits in 7th Sea) plus the score of one of their character's skills (one attribute and one skill as chosen by the player or GM based on the situation in the narrative) plus or minus other situational modifiers.
Some systems might have a core of one or more dice that are used in every dice pool. For example, in The One Ring, dice pools for resolution are built out of d6s based on the characters' stats, plus a 12-sided Feat Die that is included in every dice pool. One of the symbols on the Feat Die (representing the character of Gandalf) is an automatic success on the roll, even if a character is otherwise untrained.
Dice pools can also be built based on non-numeric stats. For instance, in the game Lady Blackbird by John Harper, dice are added to the pool based on the number of relevant tags on a character sheet. In Marvel Heroic Roleplaying and other games derived from the Cortex game engine, pools are built mainly by picking relevant traits from specified lists, with each trait represented by a specific die type (generally from d4 to d12).
While Dungeons & Dragons and related games use a fixed die (d20) for their standard determination of success and failure (rolling against a target number), they may also use dice pools to resolve the effect of an action, particularly in calculating damage dealt by a successful attack or a failed saving throw.
Sometimes, players can spend a resource or metacurrency to add additional dice to their pool.
Using a dice pool for resolutionEdit
Having assembled a dice pool, all dice in the pool are rolled and the result is processed. Different systems have different ways of determining this result, but some common methods are:
- Identifying the highest result on a single die and comparing to a target number. (The target number may be fixed or determined by another player's roll.)
- Summing together two or more dice (potentially all the dice in the pool) and comparing the total to a target number. (The target number may be fixed or determined by another player's roll.) The default approach in Cortex games such as Marvel Heroic Roleplaying is to sum the highest two dice to determine success or failure (and take a third die separately to represent the effect of a success).
- Counting number of successes, which may be determined by specific values on the dice (e.g. only odds or only evens, or only dice above a certain number) or specific symbols on non-standard dice. The total number of successes (perhaps after deducting failures, identified in a similar way) usually indicates the degree of success or perhaps a number of actions that can be performed. For example, in Chronicles of Darkness, dice pools are made of d10s and successes are counted as any dice that rolled as 8, 9 or 10.
- Grouping dice into smaller groups, possibly by matching numbers or symbols (as in, for example, the One-Roll Engine), or by combining complementary numbers or symbols (e.g. in 7th Sea, players group dice into as many groups as possible with a value of 10 or more).
When used for resolution, pools usually no longer exist after resolution has been concluded, and the dice can be used in subsequent rolls.
Permanent dice poolsEdit
Some dice pools are not built and used for a single roll, instead persisting over a period of time. A player may have a persistent dice pool for themselves, or there may be a single dice pool for the table or the GM. Game systems will usually have rules about how dice are added to and removed from the pool, as well as when (if ever) the dice should be rolled, what the result will mean and what will happen to dice that have been rolled from such a pool.
- Dice pool at Wikipedia, the free encyclopedia.