Vitality and health are two separate scores, tracked for each character.
Vitality represents the stamina of character, their current supply of vital force and energy. You use vitality when your character climbs walls, swings chandeliers and battles fierce enemies.
Starting amount of character's Vitality is always 10. You can purchase more Vitality by spending Experience points. Thus, your character will gain 1d3 Vitality for each upgrade with no upper limit.
Vitality is easy replenished when your character rests, has a good meal, unwinds outside of danger and uses other means to catch their breath.
When your character risks their life and limb but has means to prevent harm - blocking with a shield, evading a blow or parrying with the haft of their battleaxe - they can do it by spending Vitality points, if they has enough. Losing Vitality means that no real harm was done, and your character can regain it by simply taking a breath outside of combat when there is no danger nearby.
Characters regain Vitality at a rate of (1 + 1 for each Vitality upgrade purchased) per minute of rest.
For example, Ben's player purchased 3 Vitality upgrades and received 1, 2 and 2 additional Vitality for Ben's Vitality of 15. Ben would regain 1 + 3 (one for each upgrade) = 4 Vitality per minute of rest.
If your character has lost all of their Vitality, they becomes tired. The Tired condition doesn't impair your character's abilities, it only means that they have a hard time doing something strenuous like sprinting, lifting heavy things or parrying enemy attacks.
The Health score represents the amount of real physical damage your character can withstand before getting knocked out.
Starting amount of character Health is equal to 10 + your character's Body. You can purchase more Health by spending Experience points in the same way as Vitality - you gain 1d3 Health for each upgrade with no upper limit.
If your character has no Vitality left, they begin to lose Health points when hit. If there is not enough Vitality to soak all the damage from an attack, any excess damage is counted toward Health. Some nasty Special attacks and normal Critical hits inflict Health damage even if Vitality hasn't run out yet.
Losing Health means getting hurt - minor wounds, muscular, ligaments and tendons injuries, bruises, contusions and concussions all count as "Losing Health". It can be healed by natural healing capabilities if your character spend enough time in comfortable rest. Your character will get their first really nasty wound when they lose all their Health and become Knocked out
To regain Health, your character needs medical attention or a prolonged rest in safe comfortable place with little or no activity. Characters regain Health at a rate of (1 + 1 for each of Health upgrade purchased) per hour of rest. If there is a good doctor ready to treat your characters injuries, your character will regain an additional (Physician's Mind + Healing) Health per hour of rest.
When your character have less than a third of their maximum Health + number of Health upgrades purchased, they enter a Critical condition. In this state they cannot regain Vitality by resting because they are hurt enough to not be able to breath out and restore their strength. They are injured, in pain, and can only think about easing their suffering.
When character with positive Health score takes enough damage to drop to 0 Health or below, their Health drops to 0 (any excess damage is lost, except in the case of Massive Trauma). This means your character has taken a serious blow that put them on the verge of being knocked out, either due to injury, shock, pain, or just the sheer terror of the experience.
If your character has any Vitality left, that means that they have made it and could act normally at the cost of their remaining Vitality. Characters with 0 Health lose Vitality at the rate of 1 + (1 for each negative Health they have) per round, to a minimum of 0, and when they reach 0 Vitality and 0 Health, they are Knocked out.
Knocked out characters struggle to stay conscious and unable to perform any significant actions. They are completely at the mercy of those around them, be they friends or foe.
If your character is Knocked out, any more damage from any source depletes their Health as normal. In this case, your character is considered to have a negative Health.
The Knocked out condition itself does not have any long term negative effects on your character. But helplessness and mercy of foes and elements can easily kill. Your character also can be maimed, taken hostage, jailed, tortured and so on - from the very moment of knockout they cannot help themselves and become an actor in the DM's story.
But if your friend is nearby, who can lend a helping hand, everything changes. With the help of a friend, your character has every chance to wake up in the camp with their wounds tended and begin to regain their Health at a normal rate.
The rules are simple - if any enemy has a chance to deal a Killing Blow to Knocked out character, they can do so by performing a single Major action. If there is an ally nearby who protects your character's body, said enemy must instead make an attack and inflict normal damage if the attack hits. Your character also takes damage by environment, such as falling stones or extreme heat. If there no allies standing at the end of the fight, or party retreated, leaving behind the body of their friend, the fate of your character is up to DM and their decision. Otherwise, your character will likely wake up in camp.
If at any point your character's negative Health becomes equal to or more than their normal maximum Health, they will die from their wounds at that moment.
If you can put down a helpless defenseless character and you are not in danger, you can perform a special Major action - Killing blow. The target of Killing blow simple dies with no dice rolling and Health losing.
You cannot perform a Killing blow:
If your character takes so much damage from a single hit that the negative Health they would have after that hit would be equal to or greater than their normal maximum Health, they will die regardless of their Vitality, Health, and so on.
No one can survive if a mountain falls on their head.