Add your Fortitude rank to all defensive Constitution rolls.
Enhanced Vitality: You will not suffer permanent wounds from losing HP if the damage does not reduce them below half your maximum HP. You also increase your base HP by a value equal to your Fortitude rank x 2. You are able to remain conscious while at 0 HP, allowing you to fight to the brink of death for a number of turns equal to your rank + CON. However, in this state you will be fatigued and unable to perform full-round actions.
Natural armor: Your body is capable of resisting weapon attacks., granting you natural armor equal to your fortitude rank x 2. Natural armor will reduce weapon damage you suffer, but will not count as armor for the purposes of slashing blades and weapons that deal piercing damage can inflict permanent injuries if you have 0 Vitality even it reduces their damage to 0.
Resist Death: Once per combat as a reaction to being reduced to 0 HP or less you can revive to 1 HP without suffering permanent wounds. This ability cannot be used if you are exhausted, incapacitated or suffering from nausea.
Great constitution: You gain resistance against poisons, diseases and toxic gases equal to your Fortitude rank + 1. The resistance granted by this ability also works against supernatural poisons and diseases.
Rapid Recovery: Your body recovers at prodigious speeds, causing you to heal all your lost HP with a short rest. In addition, with a long rest you can reduce the level of a permanent wound by one step without the need for medical action. If you already have an ability that grants you regeneration you increase the number of Vitality that heals you per turn by 1.
Resist weapons: Once per turn as a reaction you can reduce the level of a permanent injury you receive by one step. This ability can also be used to survive an instant death attack, making it inflict you a permanent injury instead.