Each time a character suffers 1 or more points of subdual damage, if his current subdual damage total exceeds a multiple of his Constitution score (e.g. 1 × his Constitution score, 2 × his Constitution score, etc.), he must make a Fortitude save. The highest threshold exceeded by the total subdual damage accumulated to date determines this save’s DC, as shown on Table 5.9: Subdual Damage DCs. With failure, the character becomes unconsciousAn unconscious character is helpless and may take no actions. A character loses this condition after 2d4 full hours of sleep. for the listed knockout duration × 1/2 the difference between his result and the DC.
A critical hit with an attack that inflicts subdual damage forces an immediate Fortitude save, even if a threshold is not exceeded. This save’s DC is 16 (if no threshold has been exceeded) or the DC for the highest threshold exceeded +4.
At any time outside combat, subdual damage wears off according to the character’s current subdual condition, as shown on Table 5.9. Subdual damage does not wear off during combat.
Example: Kevin has a Constitution score of 10. A henchman pummels him, inflicting 18 points of subdual damage and forcing him to make a Fortitude save (DC 12). He succeeds with a result of 15, avoiding a knockout that would have lasted 1 or more rounds. In Kevin’s current state, he heals 1 point of subdual damage every minute once the combat ends.