Instead of using toughness as a measure of the number of criticals a person cal suffer before being in danger of death I suggest a flat value - 4 critical wounds.
Tougness will already soak wounds reducing the number of criticals you get in some cases.
Ideas:
- Critical threshold is 4 for everyone. If you have more wounds than your wound threshold and four critical wounds - you die.
- If you get four critical wounds, each additional critical wound will inflict normal wounds equal to it's severity.
Comments and ideas please :-)