Exploring HP variations in D&D

I’m quite aware of the many, um, dynamic arguments about the concept of Hit Points in the various Dungeons and Dragons games. Are they physical injury (the answer seems to be ‘mostly not’)? Are they a good way to represent injury (jury out, but very, very heated)? Are they realistic (clearly not, nor are they supposed to be).

For DnD-type games, how do they work at the base? 

For the record, why do I even ask? Just to level set things, including myself. It never hurts to start from a common point of reference.

Swords and Wizardry

 Hit Points are described simply as “the amount of damage one can handle before becoming incapacitated.” 

Also: “When a character (or creature) is hit, the amount of damage is deducted from hit points. When total hit points reach 0, the character is unconscious, and if hit points are brought down to –1 or lower, the character dies.”

An interesting note, and relevant to the rest of this post, is a box-text immediately after the above quote (p. 43 of S&W Complete):

A good potential house rule is attributed to Gary Gygax’sgaming table, a rumor that might or might not be true. Itallows a character to remain alive (although bleeding to deathat the rate of 1 hp/round if no assistance is rendered) until thecharacter reaches negative hit points equal to the character’slevel. In other words, a fifth-level character actually dies onlyupon reaching -5 hit points.

Comments; Well, you’re really at the razor’s edge in S&W. You’re hale and robust until you hit exactly 0 HP, and then you drop unconscious. Any negative points and, rules-as-written, you’re dead.

Dungeons & Dragons, 5th edition

This latest version of the D&D rules is more verbose about what HP are, as well as what losing them means. Quoting from the Player’s v0.2 rules:

“Hit points represent a combination of physical and mental durability, the will to live, and luck. Creatures with more hit points are more difficult to kill. Those with fewer hit points are more fragile.”

It’s pretty hard to outright kill a character, though:

Dropping to 0 Hit PointsWhen you drop to 0 hit points, you either die outright or fall unconscious, as explained in the following sections.

Instant DeathMassive damage can kill you instantly. When damage reduces you to 0 hit points and there is damage remaining, you die if the remaining damage equals or exceeds your hit point maximum.

For example, a cleric with a maximum of 12 hit points currently has 6 hit points. If she takes 18 damage from an attack, she is reduced to 0 hit points, but 12 damage remains. Because the remaining damage equals her hit point maximum, the cleric dies. 

Falling UnconsciousIf damage reduces you to 0 hit points and fails to kill you, you fall unconscious (see appendix A). This unconsciousness ends if you regain any hit points.

Comments: This basically means that if you’re hale and robust, you will fall unconscious at 0 HP, but must take damage that would bring you “fully negative” in a single blow to kill you instantly. However, the next section, “Death Saving Throws,” shows that if you have 0 HP, you will be making a Saving Throw each turn, and if you fail three of them, you die. On the average, then, unless you get a massive blow delivered, you will last about six turns before you die or stabilize.

In D&D5, then, HP are quite explicitly more than just physical injury, and include mental durability and toughness as well as luck. S&W leaves this implicit, if it’s meant at all.

Pathfinder Core Rulebook

It wouldn’t do to talk about HP without dealing with the other 800-lb. gorilla of the RPG industry, Paizo’s Pathfinder Core Rulebook.

In Pathfinder, HP “measure how hard you are to kill. No matter how many hit points you lose, your character isn’t hindered in any way until your hit points drop to 0 or lower.”

They go and define what they are, too: “the ability to take physical punishment and keep going, and the ability to turn a serious blow into a less serious one.”

If you hit exactly 0 HP, you’re disabled. When you go into negative HP territory (0 or lower), you’re disabled, unconcsious, and dying. Unconscious and Dying are both ‘conditions’ in Pathfinder, technical terms of art.

If you hit negative HP equal to your CON, you’re dead.

Comments: Still a bit of the razor’s edge, with the disabled thing starting at exactly 0 HP, but you have a buffer zone of HP equal to your CON where you’re KO’d, and then you’re dead. But KO’d isn’t really a way to stay – you’re dying and lose 1 HP per round until you actually die or are stabilized.

All D&D Variants

You gain HP every level, with a bonus for having high CON. So by the time you reach (say) 10th level, if you have (say) a 14 CON, you’ll have (as a bog-standard fighter) 75 HP in Pathfinder (on the average), 52.5 HP in S&W, and 75 HP in DnD5. 

At that level, you risk death or automatically die by taking 52.5 HP in S&W, or 75 HP in D&D5 (150 HP for ‘instant death!’), or 89 HP in Pathfinder.


What? GURPS isn’t DnD. 

No. No it is not. But it’s an interesting counterpoint. You only get more HP if you buy them, and your HP start equal to your ST. More powerful fighters avoid death by putting on armor (equivalent, sort of, to increasing AC), and having better Active Defenses (parry, block, dodge). But two characters of disparate skill and equal ST are equally easy to kill if they just stand there and don’t defend.

Edge Cases and Explicit Karma

So, with all that, what’s the point? I wonder if it would be useful or fun to hack at these concepts a bit, borrow from the best of all the systems, and come up with something that enhances the game.

Let’s start with . . . 
What’s a HP anyway?

I’m going to propose separating HP into two pools. I will call them Body and Karma. 
Your Body pool is your physical self. It’s not grit, will, skill, or luck. It’s bone and meat and represents blood and pain. You start with Body equal to your CON.
Option: Trying to decide if I should add the character’s level to this; I think yes. 
So your first level fighter with a decent CON score (say, 14) might start out with 15 body. If you don’t have level, use Hit Dice for monsters.
If these body points go to zero, you risk unconsiousness. If they go negative, you die.
Option: That rule, while simple, effectively gives more total HP. Might want to split it in two. You have Body equal to half your CON+Level (round up). You fall unconscious when you hit 0 Body. You die when you hit negative Body equal to half your CON + Level (round down). So your CON 14, first level fighter has 8 Body, and dies when he hits -7 body. A 16th level fighter with CON 16 has 16 Body and dies at -16 Body. Even that fighter is two sword strokes from KO, and four from death.

The other pool of points does represent luck, grit, skill, and mental toughness. Call it Karma, for lack of anything better. 
This is the conventional version of HP. Roll 1dWhatever just as normal, and that’s your karma pool. It gets the usual CON bonus (grit) and you get more HD per level as normal.
Why Have Both?

This helps differentiate between what is effectively fatigue and injury. If you have your AC overwhelmed by a blow, you have failed to dodge, your armor has failed to shrug off the blow. Reducing your Karma pool says that you managed to turn away at the last second (Pathfinder’s turning a real blow into a less serious one), got lucky, Legolas ‘clenched up’ (in the words of T. Stark) and just took it, or whatever. Burning karma won’t kill you.
Body, on the other hand . . . will. Getting knifed in the back by a thief? Shot from afar with no warning? Fall from a height? Yep. Bad juju, and those attacks hit Body directly.
Trading Karma for Body, and vice versa

One interesting thing would be to allow attacks that would otherwise be just applied to Body to be traded for karma. A lot more karma. 
You may reduce body injury taken down to as low as 1 Body (but never zero). Whatever the fraction you reduce the Body by, increase karma loss by that much!
Example: A 5th level fighter has CON 14, giving him 10 Body, and he dies at -9. He also has 38 karma points. He’s been fighting a bit, and is down to 34 karma points, and thanks to a poison trap, 4 body. A nasty, sneaky ninja knifes him in the armpit – this is an attack normally applied directly to Body. He rolls 2d4 damage and scores 8. Our fighter doesn’t feel like taking this much injury directly; he wants to stay conscious, and 8 body applied to his remaining 4 would leave him KO’d. Instead, he shifts it, taking 2 body (a 4x reduction), but to do that he has to take 4×8 = 32 karma points. He’s alive, conscious, and fully functional, but he’s at 2 Body and 2 karma remaining – his luck is about to run out.
Excess Karma

Once your karma runs out, you take damage 1:1 into your Body. If you have 10 karma and 8 Body, and take 12 HP damage, you’re at 0 Karma and 6 Body.
This might make the “trade body for karma” example above a math exercise, though. If you have the choice of taking 4 Body, 2 body and 8 karma, 1 Body and 16 karma, it’s a steady dose of “how much karma can I give up at the cost of diminishing returns in Body loss?” 
Maybe that’s not a bad thing.
What does Body?

Certain damage types should do straight-up body. A backstab, poison, falling damage, certainly. It would make spells like a 1d4 Magic Missile terrifying if they applied themselves directly to Body.
Parting Shot

The characterization of HP loss as sometimes due to injury, sometimes mental grit, sometimes luck bothers some people – I got the feeling during +Jonathan Henry‘s Giant Dragon Gamer Chat on Saturday night that +Gerardo Tasistro despised that vagueness with the fiery passion of 1,000 suns. 
My initial thought – not much different than what’s on this post – was that an explicit separation of “these points represent grit and skill; these others are your flesh and bone” might bridge this divide in a way that provides an acceptable balance.
It would also be quite interesting to look at the intersection of damage type (Pathfinder and D&D, for example, includes bludgeoning, slashing, and piercing) with Karma and Body. A bashing weapon might be 1:1 – you take body and karma in equal measure. Slashing weapons like swords might soak karma a 1:1, but any remaining body is doubled. Piercing weapons might get triple or quadruple body!
That would make the usual club, mace, sword, axe, spear, arrow thing look like this (let’s assume 3;1 for piercing) using the figures in the D&D5 book, against an Orc (CON 16, HD 2. Body 8, Karma 15).
Weapon          Usual Damage     Hit Karma       Hit Body      Max First Hit          Max Second Hit
Club             1d4 bludgeon    1d4              1d4            4 HP karma          4 HP karma
Longsword    1d8 slashing      1d8              2d8            8 karma               7 karma, 2 body 
2H Battleaxe 1d10 slash        1d10            2d10           10 karma             5 karma, 10 body
Spear            1d6 piercing     1d6              3d6             6 karma              6 karma
In this paradigm, if you can actually strike home with a thrust spear, the 3:1 piercing multiplier makes it a serious threat, equal to a sword or two-handed battleaxe at the high end.
Obviously this would require playtesting to see if it adds to the fun. But having two different pools like this would allow some interesting trade-offs. You could perhaps spend from your karma pool to do extra damage, for example. You’d not do it to avoid a blow – that’s what losing karma is already – but it might be a buy-in for certain Feats, too.
It would also allow the short rest thing to make a lot more satisfying sense. A short rest – a psychological siesta plus time to chill out – would certainly bring back karma . . . but not body. For that, you need healing potions or real time to mend.

11 thoughts on “Exploring HP variations in D&D

  1. The root of hit points are found in the Chainmail Miniature Wargame. In Chainmail, one of D&D's progenitors, A Hero is worth four veteran fighters, takes 4 hits to kill. A Super-Hero, is worth eight veteran fighters taking eight hits to kill. If you look at the class and level charts of OD&D and AD&D, a 4th level fighter is titled a Hero, and a 8th level fighter a super hero.

    In OD&D 1 chainmail hit was expanded to 1d6 damage, 1 hit to kill was expanded to 1d6 hit points (roughly). This was done because 1 hit = 1 kill for a starting veteran fighter was found by Dave Arneson to be too deadly and ultimately uninteresting. Gygax agreed and thus this the mechanic that found it way into OD&D.

    For all the rationalizing about hit point that what the mechanic is. It not like GURPS where the hit points is grounded in a simulation of real life or genre characteristic of individual characters. It represents the fact that more experienced/heroic fighters (the Hero, or Super-Hero) are harder to kill. It persisted because partly because of D&D's network effect and partly because it a easy mechanic to grasp and eminently gameable. It is also one of few mechanics that has survived from OD&D relatively unchanged.

    1. Rob, those are great insights into the history of the hobby. I'm not as familiar with that as I possibly should be, since I think the chain mail and original game came out when I was roughly 4.

  2. I do like the 2 pools method. I liked it when I first encountered Hit Point/Structural Damage Capacity pool method in Rifts/Palladium and still think they work well and could be easily applied to any system. They were used in much the same way. SDC damage? hurts, but shrug it off and keep going. take even 1 HP damage? that's serious, time to consider alternative actions.

  3. My main concern when it comes to modeling damage is not so much the realism of the model, but the realism of the effects of such model. I've come to focus more on how the way a game handles damage (realistic or not) affects how players play their characters and what options are open for them.
    The conversation on this topic spawned from tactics. Namely the inability of a party to quickly neutralize the enemy (within the first round or two). This leads to options and strategies being locked away because, although they are plausible, the hit point mechanics prevent them from taking place.

    1. Right, and that's where the differentiation between Body and Karma comes in. If you can negate the foe's Karma, you can potentially engage in a one-round ambush situation that has a fight basically over before it starts. You know, the goal of all tactics!

    1. It might be! The rule was generated from the conversation, but I am not intimately familiar with all 600 pages of Pathfinder. This is especially true since I have never game mastered the system, only played it.

    2. Thanks – I'll have to look at this when I get home. My work firewall slams shut on this, since it's "games and porn." Or maybe just "games." Same difference, really. That's the real origin of playing D&D (games) with Porn starts (self-referential), ya know. 🙂

  4. It's interesting that people keep reinventing this method, and I completely understand the impulse. I note that it was used in the WotC version of Star Wars, and the "karma" equivalent also functioned as spell points for many of the magic abilities ("force powers").

  5. "On the average, then, unless you get a massive blow delivered, you will last about six turns before you die or stabilize."

    Minor nit: the math actually works out to an expected number of rolls of 3.6275 (assuming no extra damage). Note that because you'll always either die or recover after at most 5 rolls and there are ways to die/recover faster, the average must be less than 5.

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