Upon encountering an unnerving or horrifying situation, the investigator makes a SAN Roll: Upon a success, the player records a new Current Sanity by subtracting the Success Sanity Loss from their Current Sanity. If the roll fails, the player records their new Current Sanity by subtracting the Failure Sanity Loss. The investigator experiences a brief involuntary reaction, chosen by the keeper. This loss may result in one of the following three types of insanity.
- If an Investigator’s Current Sanity is now at 0, the Investigator suffers Permanent Insanity.
- If an Investigator loses 20% or more of their Sanity held at the start of the current game day, they suffer from Indefinite Insanity including a Bout of Madness.
- If an investigator loses 5 or more Sanity points from a single source of Sanity loss, the Investigator will attempt to suppress the truth by making an INT roll. If the INT roll succeeds, the investigator suffers Temporary Insanity including a Bout of Madness. If it fails, the memory is repressed, and no insanity occurs.
Sanity loss from Mythos sources effect Chtuhlu Mythos Skill KHB p.163
Reassure Skill: May recover a small amount of Sanity (Keeper-determined or scenario-defined), or may reduce the impact of recent mental strain (such as stabilizing after a shock or preventing escalation) Cannot be used during a Bout of Madness. Typically limited to once per event or situation per target (Keeper discretion) (Mike Mason has stated that this can be included in any Call of Cthulhu game, in a 2026 episode of Modern Mythos.) CBG IG p.95
- SAN Rolls and Sanity Loss Notation: KHB p.154
- Current Sanity vs Maximum Sanity: KHB p.155
- Bout of Madness KHB p.156
- Indefinite Insanity KHB p.156
- Temporary Insanity KHB p.155
- Permanent Insanity KHB p.156