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Dice mechanics

Dice pool basics in Call of Cthulhu 7th Edition

Rolling multiple dice and counting successes.

Explanation

Call of Cthulhu uses percentile skills: roll d100 and succeed if you roll at or under your skill. Difficulty often shifts the threshold (Regular/Hard/Extreme) and Sanity loss is a core pressure loop.

At the table (quick loop)
  • Pick the relevant skill (e.g., Spot Hidden, Library Use).
  • Roll d100 and compare to your skill rating (and difficulty threshold).
  • Apply consequences: information gained, complications, or Sanity loss when appropriate.
Example: Spot Hidden 55%: a roll of 42 succeeds; a harder threshold would require a lower roll.
Examples
Example: build the pool

Pick the two traits that match your approach (often Attribute + Skill), roll that many d10s, then count successes.

Example: raise/lower difficulty

Instead of stacking small modifiers, change the difficulty (required successes) so the decision is readable.

Common mistakes (smallest fix)
  • Mistake: Rolling without a clear pool. Fix: Say the approach, then pick the two traits that define the pool.
  • Mistake: Counting successes inconsistently. Fix: Keep one quick reference open (cheat sheet) during play.
More dice mistakes

Call of Cthulhu 7th Edition FAQ

How does the percentile system work in Call of Cthulhu?
How does the skill improvement system work?
What are the Characteristics in Call of Cthulhu 7e?
How does Sanity work in Call of Cthulhu?
What are Occupations in Call of Cthulhu?

Keep play fast

Use quick references, then jump back into the scene.