When a Contractor attempts an action where the outcome is risky or unsure, the GM will call for a roll to help them determine what happens.
The GM names one Attribute, one Ability, and a Difficulty. The Player rolls a number of ten-sided dice (d10s) equal to the sum of their Contractor's ratings in the named Attribute and Ability. The number of dice rolled is called the Dice Pool. The value used to determine whether an action succeeds or not is called the Outcome.
The Outcome starts out at 0. Each die that lands on a number equal to or greater than the Difficulty gives +1 to the Outcome. A die showing '1' is called a "botch" and subtracts 1 from the Outcome. A die showing a '10' is called a "double" and gives +2 instead of +1 to the Outcome (some D10s may show a 0 instead of a 10, but they are counted as 10s).
Based on the total Outcome, the action succeeds or fails:
|<0||A botch. Something goes horribly wrong.|
|0||The attempt fails.|
|1-3||The attempt is partially successful or is successful but has a complication.|
|4-5||A complete success, things go as planned.|
|6+||An exceptional success. The action is performed with grace or has an additional, positive effect.|
The specific details of how the action occurs are up to the GM to determine, but most rolls should follow the above scale, unless a different mechanic is specifically described, such as for Contested Actions (see below), or for a number of Powers.
Player: "I climb the ivy-covered wall to the third-floor balcony."
GM: "Roll Dexterity plus Athletics, Difficulty 6"
The Player looks at their burglar's Character sheet and adds their rating in Dexterity (4) and Athletics (3) for a total Dice Pool of 7. They roll 7 10-sided dice:
2, 6, 0, 8, 1, 5, 7
(0 +1 +2 +1 -1 +0 +1) = 4
The Outcome is 4, a complete success. The GM declares that they make their way up the ivy, snapping a few twigs and leaves along the way before pulling themselves up onto the balcony.
An Outcome of 6 or greater would have resulted in a particularly quick climb that did not leave any trace. An Outcome of 1, 2 or 3 would have resulted in making it to the balcony, but might have caused substantial damage to the ivy or made enough noise to catch the attention of someone inside the mansion.
A failure (Outcome of 0) might mean that they can't figure out how to get a grip on the ivy without destroying it. A Botch (-1) would probably have resulted in them making it nearly to the balcony, then falling painfully to the ground.
When two Characters enter into a contest of skill (e.g. sneaking past a guard, parrying a sword attack, or competing in a race), the action is considered Contested. This happens often in Combat.
In Contested Actions, both parties make a roll. The defender's Outcome is subtracted from the attacker's, reducing it to a minimum of 0. Because of this, ties go to the defender. For Contested Actions, any resulting Outcome greater than 0 is considered a complete success.
Each Character may have a different roll. For example, sneaking past a guard would be Dexterity + Stealth versus Perception + Alertness. The default Difficulty for contested actions is 6, but this can be modified by the GM as normal, often resulting in Difficulties that are different for each participant. For example, if it is very dark or noisy, the Guard might be asked to roll their Perception + Alertness check at Difficulty 7 or 8.
The Dice pool and Difficulty of each roll may be subject to modifiers that make success more or less likely.
For example, if you are attempting to sneak down an alley but do not have any Stealth, you may roll only Dexterity, but the Difficulty will be 7 rather than 6.
Difficulty can be increased or decreased by situational factors at the GM's discretion. For instance, investigating a dark room with your cell phone's flashlight would be rolled at +1 Difficulty. Swimming with a life vest would be -2 Difficulty.
The final, modified Difficulty cannot be reduced below 4. If the Difficulty of a roll would ever rise above 9, instead, the Difficulty stays at 9 and your total Dice Pool is reduced by the overage. For example, a Difficulty 12 roll with 6 dice would be rolled as a Difficulty 9 roll with 3 dice.
See the Supplementary Combat Rules for more details on Difficulty modifiers.
Dice Pool Modifiers
Some Powers, items, or effects may give Characters a bonus to certain dice pools. Bonuses to the same dice pool do not stack. Instead, the highest value is used.
For Example, if turning into a werewolf gives you +1 dice to Brawn rolls and a different bonus that gives you +3 dice to Brawl attacks, if you roll to bite someone, it would be Brawn + Brawl + 3 dice (the higher of the two bonuses).
See Dice Probabilities Calculator for more information about probabilities and how GM discretion should be used when making rolls.