Set a skill, then roll.
Exact Odds
Worked out from every combination of the units die and the tens dice, not by simulation. A bonus or penalty die changes these numbers more than you might expect.
| Result | Chance |
|---|
Luck
Spending Luck and Luck recovery are optional rules. Luck lowers a skill or characteristic roll point for point. It can't change a critical, a fumble, a pushed roll, or a Luck, Sanity or damage roll, and a roll changed with Luck earns no improvement tick. Recovery: roll d100 at the end of a session; if it's over your Luck, gain 1D10 (to a maximum of 99).
Sanity Roll
Write the loss the usual way, such as 0/1D3, 1/1D6, 1D4/1D10 or 1D6/1D20+1.
Damage
An Extreme success on an attack does maximum weapon damage; an impaling weapon (a blade or a bullet) also adds a second roll of its dice. Whether the damage bonus is maximised too is worded differently in different printings, so this roller rolls it normally; ask your Keeper. Damage bonus applies to melee, not firearms.
Reading the Roll
- Regular success: at or under the value. Hard: at or under half. Extreme: at or under a fifth. Half and fifth round down, so a skill of 55 has Hard 27 and Extreme 11.
- Critical: a roll of 01. Fumble: 100 always; when the number you need is below 50, 96 to 100. That is the number you need for this roll, so a Hard or Extreme roll can widen the fumble range.
- Bonus and penalty dice: roll an extra tens die and keep the better (bonus) or worse (penalty) tens. One of each cancels out; never more than two either way. A tens die of 00 with a units die of 0 reads 100.
- Pushing: a failed skill or characteristic roll can be rolled once more if your investigator tries a new approach, but failing a pushed roll brings something much worse. Luck, Sanity, combat and damage rolls can't be pushed.
- Sanity: lose 5 or more in one roll and make an INT roll. On a success you understand what you saw and go temporarily insane; on a failure the memory is pushed away and you stay sane, for now. Lose a fifth of your current Sanity in one day and the insanity is indefinite.
Where to Go Next
- Game Mechanics: Success levels, opposed rolls, pushing and combat in full.
- Sanity: What the Sanity roll does to an investigator.
- Playing Call of Cthulhu Solo: The same percentile dice turned into a yes/no oracle.