Damage is meted out in hit points. [...] Hit points reflect both the actual physical ability of the character to withstand damage—as indicated by Constitution bonuses—and a commensurate increase in such areas as skill in combat and similar life-or-death situations, the “sixth sense” which warns the individual of some otherwise unforeseen events, sheer luck, and the fantastic provisions of magical protections and/or divine protection.
When a character loses hit points in combat or to some other attack form (other than being drained of life energy levels), there are a number of different means by which such points can be restored. Clerics and paladins are able to restore such losses by means of spells or innate abilities.
Magical devices such as potions operate much the same way, and a ring of regeneration will cause automatic healing and revitalization in general of its wearer. Commonly it is necessary to resort to the passage of time, however, to restore many characters to full hit point strength.
For game purposes it is absolutely necessary that the character rest in order to recuperate, i.e. any combat, spell using, or similar activity does not constitute rest, so no hit points can be regained. For each day of rest a character will regain 1 hit point, up to and including 7 days.
However a character with a penalty for poor Constitution must deduct weekly the penalty score from his or her days of healing, i.e., a -2 for a person means that 5 hit points healing per week is maximum, and the first two days of rest will restore no hit points.
After the first week of continuous rest, characters with a bonus for high Constitution add the bonus score to the number of hit points they recover due to resting, i.e., the second week of rest will restore 11 (7 + 4) hit points to a fighter character with an 18 Constitution.
Regardless of the number of hit points a character has, 4 weeks of continuous rest will restore any character to full strength.
If any creature reaches 0 or negative hit points, it is dead.
When any creature is brought to 0 hit points (optionally as low as -3 hit points if from the same blow which brought the total to 0), it is unconscious.
In each of the next succeeding rounds 1 additional (negative) point will be lost until -10 is reached and the creature dies.
Such loss and death are caused from bleeding, shock, convulsions, non-respiration, and similar causes. [...] Certain magical means will prevent actual death, particularly a ring of regeneration.
It ceases immediately on any round a friendly creature administers aid to the unconscious one. Aid consists of binding wounds, starting respiration, administering a draught (spirits, healing potion, etc.), or otherwise doing whatever is necessary to restore life.
Any character brought to 0 (or fewer) hit points and then revived will remain in a coma for 1-6 turns. Thereafter, he or she must rest for a full week, minimum. He or she will be incapable of any activity other than that necessary to move slowly to a place of rest and eat and sleep when there. The character cannot attack, defend, cast spells, use magic devices, carry burdens, run, study, research, or do anything else. This is true even if cure spells and/or healing potions are given to him or her, although if a heal spell is bestowed the prohibition no longer applies.
If any creature reaches a state of -6 or greater negative points before being revived, this could indicate scarring or the loss of some member, if you so choose. For example, a character struck by a fireball and then treated when at -9 might have horrible scar tissue on exposed areas of flesh - hands, arms, neck, face.
It is quite unreasonable to assume that as a character gains levels of ability in his or her class that a corresponding gain in actual ability to sustain physical damage takes place. It is preposterous to state such an assumption, for if we are to assume that a man is killed by a sword thrust which does 4 hit points of damage, we must similarly assume that a hero could, on the average, withstand five such thrusts before being slain! Why then the increase in hit points?
Because these reflect both the actual physical ability of the character to withstand damage — as indicated by Constitution bonuses — and a commensurate increase in such areas as skill in combat and similar life-or-death situations, the "sixth sense" which warns the individual of some otherwise unforeseen events, sheer luck, and the fantastic provisions of magical protections and/or divine protection. Therefore, Constitution affects both actual ability to withstand physical punishment hit points (physique) and the immeasurable areas which involve the sixth sense and luck (fitness).
Harkening back to the example of Rasputin, it would be safe to assume that he could withstand physical damage sufficient to have killed any four normal men, i.e. more than 14 hit points. Therefore, let us assume that a character with an 18 Constitution will eventually be able to withstand no ess than 15 hit points of actual physical damage before being slain, and that perhaps as many as 23 hit points could constitute the physical makeup of a character. The balance of accrued hit points are those which fall into the non-physical areas already detailed. Furthermore, these actual physical hit points would be spread across a large number of levels, starting from a base score of from an average of 3 to 4, going up to 6 to 8 at 2nd level, 9 to 11 at 3rd, 12 to 14 at 4th, 15 to 17 at 5th, 18 to 20 at 6th, and 21 to 23 at 7th level. Note that the above assumes the character is a fighter with an average of 3 hit points per die going to physical ability to withstand punishment and only 1 point of Constitution bonus being likewise assigned. Beyond the basic physical damage sustained, hits scored upon a character do not actually do such an amount of physical damage.
Consider a character who is a 10th level fighter with an 18 Constitution.
This character would have an average of 5½ hit points per die, plus a Constitution bonus of 4 hit points, per level, or 95 hit points! Each hit scored upon the character does only a small amount of actual physical harm—the sword thrust that would have run a 1st level fighter through the heart merely grazes the character due to the fighter's exceptional skill, luck, and sixth sense ability which caused movement to avoid the attack at just the right moment. However, having sustained 40 or 50 hit points of damage, our lordly fighter will be covered with a number of nicks, scratches, cuts and bruises. It will require a long period of rest and recuperation to regain the physical and metaphysical peak of 95 hit points.
The character faces death in many forms. The most common, death due to combat, is no great matter in most cases, for the character can often be brought back by means of a clerical spell or an alter reality or wish. Of course, recovery of damage sustained might be a problem, but that is not insurmountable.
When a character loses a level of energy, he or she loses an experience level. That is, he or she loses hit points equal to those gained with the acquisition of the former experience level (including bonus points for Constitution), all abilities gained with the experience level now lost, and experience points sufficient to bring the total possessed to the mid-point of the next lower level.
If this brings the character below 1st level of experience, then the individual is a 0 level person never capable of gaining experience again. If a 0 level individual is drained an energy level, he or she is dead (possibly to become an undead monster).
In order to allow for the possibility of the loss of hit dice due to energy level draining, you might require that players record the score of each hit die rolled for their characters, so that when a level is lost the appropriate number of hit points also lost can be known immediately.
A multi-classed character (or character with two classes) who is drained of an experience level always loses the highest level he or she has gained (e.g., a halfling 2nd level fighter/3rd level thief would lose one level of thieving ability). If all levels are equal, the highest level of the class which requires the greatest amount of experience points is lost.
If a multi-classed character (e.g., a fighter/magic-user) is struck by a creature which drains two levels, a level is drained from each class.
When a character is drained of all energy levels, he or she might become an undead monster of the same sort which killed him or her. (See the appropriate paragraphs pertaining to the undead monsters concerned in the MONSTER MANUAL.) These lesser undead are controlled by their slayer/drainer. Each has but half the hit dice of a normal undead monster of this same type.
Lesser vampires have but half their former level of exerience with respect to their profession (cleric, fighter, etc.) at the time they initially encountered and were subsequently slain/drained by their now-master vampire, i.e., an 8th level thief killed by a vampire, even though drained to below 0 level in the process, returns as a 4th level thief vampire, as appropriate. However, upon the destruction of their slayer/drainer, such lesser undead gain energy levels from characters they subsequently slay/drain until they reach the maximum number of hit dice (and their former level of class experience as well, if applicable) appropriate to their type of undead monster.
Upon reaching full hit dice status, they are able to slay/drain and control lesser undead as they once were.