Core Mechanic
Any time an Action’s outcome is in question, it is resolved by rolling a 20-sided die (d20). If you roll equal to or under a target number, you succeed, this is known as Rolling Under. For example, if the target number is 15, you Rolled Under and succeed. Otherwise, you Rolled Over and fail.
Checks
A Check occurs when you attempt an Action where success is not guaranteed.The GM should only roll or ask for a Check if the outcome of an Action is in question. If success or failure is near guaranteed, there is no need to roll.
To make a Check, the GM chooses the Stat that is most relevant to the Action your Adventurer is taking, then you attempt to roll under that Stat on a d20.
In certain circumstances, a GM may want to add a modifier to a roll to represent a particularly difficult task. In these situations, the GM will add a +3 to the player's roll. GMs should inform players of these modifiers before they choose whether or not to take an Action.
For example…
Dodging an Explosion. An Adventurer is standing at the edge of an explosion. They roll an Agility Check to dive behind cover. The Adventurer’s Agility is 13; they roll an 8, so they successfully dive behind cover and avoid the explosion's damage.
Kicking open a door. An Adventurer wants to kick down a door in a hurry. They roll a Brawn Check. The Adventurer’s Brawn is 14; they roll a 15, so they fail to kick the door down. If the Adventurer were not in a hurry, a roll would not be necessary here, as there would be no consequence for trying again as many times as it takes to break the door.
Opposed Rolls
When two characters take Actions that are directly opposed to each other, an Opposed Roll occurs. Like a normal Check, the GM chooses the most relevant Stat for each character's Action, and both parties attempt to roll under their stat. Both characters attempt to roll under the relevant Stat. Whoever rolls under by more succeeds. If both characters roll over, the character who rolled over by less succeeds, or neither character succeeds, depending on the situation. Ties go to the character with the higher Stat.
For example…
Grappling. An Adventurer wants to hold a Cambion in place. The GM asks for an opposed Brawn Check. The Adventurer’s Brawn is 14, the Cambion’s is 12. The Adventurer rolls a 10, and the Cambion rolls a 9. The Adventurer has rolled 4 under their Brawn, while the Cambion has rolled 3 under theirs. The Adventurer succeeds and is holding the Cambion in place.
Racing. Two Adventurers want to grab an idol before the ground gives way beneath it. The GM asks for an opposed Agility Check. They both have an Agility score of 11. Adventurer one rolls a 13, and Adventurer two rolls a 14. Since both rolled over, the GM could award the victory to Adventurer one, but they instead decide that neither succeeds, and the ground beneath the idol crumbles before either Adventurer can reach it.
X in 6 Rolls
Sometimes, the outcome of a situation comes down to chance. In these cases, the chance of a certain outcome will be expressed as X in 6. This means you roll a d6, and if the result is equal to or lower than X, the outcome occurs.
For Example…
Eye Injury. A Trick Shooter wants to Attack an enemy, but is suffering from a gauged eye, giving him a 5 in 6 chance of hitting. The Trick Shooter rolls a d6. The die comes up 4, so the Attack hits! If the Trick Shooter had rolled a 6, the Attack would have missed.