How rolls work
Dice mechanics
Short, linkable explanations of core dice mechanics, organized by system.
“Roll a d20” means something different in every game on this site. Vampire counts successes across a pool of d10s against your Hunger. Call of Cthulhu rolls percentile dice under a skill rating. Daggerheart reads two d12s for Hope and Fear. The die is never the whole mechanic, what you do with the result is.
Each mechanic below gets one page per system: what you roll, how you read the result, what counts as a critical or a fumble, and how modifiers stack. Pick a mechanic, then pick your system, and you get the version that matches the actual rules, not a generic explanation.
Mechanics
Dice pool basics
Rolling multiple dice and counting successes.
Criticals & fumbles
How critical results usually work.
Contested rolls
Opposed checks and ties.
Modifiers
Bonuses, penalties, and situational adjustments.
Frequently asked questions
Why do dice mechanics differ between systems?
Do these pages replace the rulebook?
Where do I roll these dice?