Rules Reference

Core Dice Checks & Success Levels

How skill and characteristic rolls work in Call of Cthulhu 7th Edition (Critical, Extreme, Hard, Regular, Failure, Fumble).

Bonus and Penalty Dice

Rules for rolling multiple tens dice when circumstances provide significant advantages or hindrances.

Bonus Die (+1): Roll 2 tens dice, take lowest total. Penalty Die (-1): Roll 2 tens dice, take highest total.

Pushing Skill Rolls

The high-stakes mechanic allowing an investigator to re-attempt a failed roll by taking extra risks.

Justify the extra risk -> Re-roll 1d100. If fail: severe dire consequence occurs. Combat & Sanity cannot be pushed.

Opposed Rolls & Resolving Ties

How contested actions between two active characters (e.g. Stealth vs Listen, Grapple vs Dodge) are resolved.

Critical > Extreme > Hard > Regular > Fail. Ties broken by higher base skill value.

Luck Spending & Luck Recovery

The optional and standard rules for spending Luck points to alter dice rolls.

1 Luck per 1 point deducted. Cannot spend on Luck rolls, Sanity, Damage, Pushed rolls, or Fumbles.

Sanity, Trauma & Insanity System

Complete mechanics for Sanity loss, Involuntary Actions, Temporary, Indefinite, and Permanent Insanity.

5+ SAN in 1 turn + INT check passed -> Bout of Madness (1d10 rnds/hrs). 1/5 SAN in 1 day -> Indefinite Insanity. 0 SAN -> Permanent Insanity.

Bouts of Madness Tables (1d10)

The official Real-Time and Summary tables for determining the specific behavior during a Bout of Madness.

Combat, Fighting Back & Maneuvers

Call of Cthulhu 7th Edition combat sequence, attacker vs defender resolution, maneuvers, and outnumbering.

Initiative by DEX. Defender chooses Fight Back (highest success hits) or Dodge (equal/higher avoids). Outnumbered defenders grant +1 Bonus Die.

Firearms, Cover & Point Blank Range

Gunplay mechanics, dive for cover, firing bursts, range penalties, and firearm malfunctions.

Point-Blank (< DEX/5 ft): +1 Bonus Die. Dive for Cover imposes -1 Penalty Die (defender knocked prone). Malfunction rate triggers gun jam.

Wounds, Major Wounds, Dying & Healing

Hit Points, Major Wounds, unconsciousness, dying states, First Aid, Medicine, and recovery rates.

Single hit ≥ half Max HP -> Major Wound. HP 0 with Major Wound -> Dying (needs First Aid stabilization). First Aid = +1 HP; Medicine = +1d3 HP.

Living Standards & Credit Rating

The 6 economic tiers from Penniless to Rich, daily cash allowances, and asset calculations in Call of Cthulhu 7th Edition.

Forensic Science in the 1920s

What forensic investigation methods and technologies were available to 1920s investigators vs modern capabilities.

Available: Fingerprints, ABO blood types, Ballistics comparison microscope, Chemical toxicology. Unavailable: DNA, digital search, luminol.

1920s Slang & Terminology Dictionary

Common period slang, idioms, and phrases used in roleplaying 1920s Call of Cthulhu games.