Hit Points: Getting Real
Imagine you're a first level D&D character who's out there slugging it out. A sling stone creases your head. While you're reeling from that, someone gets in a lucky strike and now your sword arm is bleeding. It's not too deep, but it's painful, and you really kind of need that arm.
In real life, how bad shape are you in? How close to being taken out are you? These are both good questions, but not questions that can be answered by examining precisely how much "damage" you've taken in some quantifiable numerical terms.
In D&D terms, a first level character with these wounds (one hit from a skilled slinger, one hit from a skilled sword slinger) might very likely be bloodied, the state of having lost half of one's hit points.
In mechanical terms, if you've lost half your hit points from two attacks then a couple of further hits just like them could put you down. Is this plausible?
In real life, one sling stone to the head or one blow from a sword can kill, so if there's any verisimilitude at all to this we have to assume these aren't those kinds of hits. On the other hand, what kind of hit from a sling is just deadly enough that about four of them will knock you unconscious and about six of them will kill you?
Unless we're assuming that the stones are hitting the same spot again and again, I don't think that really works as a model. Even then it's extremely iffy. And yet in the game, a character with, say, 24 HP who gets hit four times for an average of, say, six HP per attack will be knocked unconscious and in danger of dying in the course of things, especially if "the course of things" includes two more hits like that.
How can this work? How can this be realistic?
And then say you've taken two sling hits, or a sling hit and a sword-stroke, and you're bloodied... you take a deep breath, square away your shoulders... or your friend the Warlord shouts out some encouragement... and suddenly, without any magic or divine intervention, you're so much less closer to being dead that it will take another hit to knock you out or kill you.
You've also lost something called "a healing surge", but you're not sure what that's supposed to be.
Can this make any kind of sense?
I really think so.
First, Hit Points will never make sense if you think of them as how much blood or life force your character has left, or anything of that nature. It's not a measurement of structural integrity. Likewise, having lost half of one's hit points isn't in any way the same thing as being beaten half to death. Even the name "bloodied" suggests that. It might not be the exact point at which you start bleeding, with no blood shed at all before, but it's the point at which your enemies can see that you're hurting.
To understand what hit points do represent, we have to look at what they mean in the game. Hit points, especially in 4E, define one thing: are you in the fight, or aren't you? It's a boolean operation... one or the other, not both, and no in-between values. When your hit points are positive, you're able to keep fighting. When they're not positive, you're down and possibly dying.
So if hit points are a measurement of anything about your character, they're a measurement of one's ability to keep fighting on. To return to my initial example of a creased forehead from a sling shot and a stinging arm wound from a sword: these are not things that are going to be immediately fatal. These are not things that are going to cause a warrior or adventurer of any description to fall down on the field of battle in the brief time it takes for the skirmish in which they were received to be concluded. They are wounds that can be pushed aside and ignored until the day is won (or lost).
But say you take a couple more hits that are just as bad... can you suck it up and ignore them? Possibly. But no matter how much we might be inclined to think of death and dismemberment as being basically scientific... matters of simple biology... Stuff That Hurts But Doesn't Kill You is a much grayer area. If your leg is injured but not missing or completely physically incapacitated, whether or not you keep standing on it can be a function of your resolve, your ability to dig down and push past the pain. Hit points model the erosion of that resolve much more closely than they reflect gross physical damage. This is why attacks that unnerve or cause discomfort might do "psychic damage" that comes off the same HP total as the non-proverbial slings and arrows aimed your way.
I've spent a lot of space describing something that most veteran D&D players are aware of... namely, that hit points are an abstraction rather than a simulation. But my goal in writing this is to help people see that this doesn't have to blunt the realism or plausibility of what happens in a combat encounter. Indeed, keeping this idea at the forefront of the mind can only help make combat more believable.
If your conception of hit points leads you to believe that someone who's lost half of them to acid damage should have acid burns over half their body, and the game's telling you that a couple of inspiring words or a night's sleep will make those acid burns go away, then of course your suspension of disbelief is going to do a bit of a nosedive. But that's predicated on a false belief. Even if you get down to 0 HP from acid attacks, that doesn't necessarily mean you have massive burns all over your body. It just means that the burns you do have are more than you can withstand at the moment.
This also makes it easier to understand how you can take foes alive when you're swinging blades and such at them. You took away all their HP, doesn't that mean they're dead or almost dead? No, it means they're out of the fight... rendering someone hors de combat is not the same thing as rending them hors de corps.
There is an intersection between what HP represent... that is, your "fightin'-ness"... and what many people assume they represent, your bodily health. This is why things that are meant to literally heal your body tend to restore HP. The terms "healing" and "restoring HP" are used interchangeably, in the same way that "damaging" is understood to be the same as "costing HP"... conventions that can muddy the waters a bit. And it's true that you will still run into places where abstraction leads to logical fuzziness... like when herbs and bandages restore HP that were lost to a Bard's vicious taunt or a purely mental psionic assault... or when there is no supernatural healing available to the party but there is still no lasting damage no matter how badly injured everybody is how often... but in most cases there will be a mixture of damage types being suffered and a mixture of healing sources being used, so it can be assumed that all these disparities are coming out in the wash.
Your teammate puts a poultice on your physical wounds and this helps you forget about the psychic ones. Everybody in the party's getting enough of the healing potions or the Cleric's healing prayers or other magical goodness that there's no need to worry about scarring and long term effects. And so on.
So What Are Healing Surges, Then?
When you reach down deep within yourself and find the strength to keep fighting, your Healing Surges represent what you're digging into. Much like HP, they stand at an intersection of physical health and mental resolve, but they work on a macro level of how much punishment you can take over the course of a day rather than how much you can take and keep fighting.
Sometimes people who are just learning the system--particularly if they're coming straight from a previous edition--learn what Healing Surges are and say, "Okay, so if you've got 20 HP and 7 Surges, then you've basically got 55 HP." That's an oversimplification, and like most oversimplifications it shrinks the topic at hand so small that the truth no longer fits within it. The character under discussion might generally go through 30 of their supposed 55 HP in a fight before being knocked out of it. Each of those surges can only be used situationally, and while many of the situations are frequent and under player control (outside of combat, anyway), there are fewer things like magical healing items, and those that remain tend to take a surge anyway.
A character with 20 HP and 7 surges isn't the same as a character with 55 HP. It's a character with 20 HP and the potential to shake off 5 HP worth of damage seven times a day, as long as they have some room to breathe or a bit of help from a friend. There's a considerable difference.
People who believe that 4th Edition D&D lacks verisimilitude... the quality of seeming real... often ask questions like "What is a Healing Surge? What does it really represent? Where is it found on the body?" It's more instructive to think about what a spent Surge represented than what the ones remaining in the pool do. If you take grievous injuries and you use your Second Wind to spend a surge, it might represent those injuries and their cumulative effect on your body. You've "healed HP", but in the reality of the game the injuries don't disappear. If the injuries are something that might be more painful and less actually damaging (remember, this would be a function of what the injuries are according to the narrative, not how many HP they took off), the spent Surge might represent the fatigue it caused. In "shrugging off" these things with a Healing Surge, you're not negating the fact that the damage happened, you're just moving it from an immediate concern to a slightly longer-term one.
Is this realistic? Here's reality for you: I fell down the stairs a few months back and twisted the heck out of my ankle. Painful? There was no way I could stand on it, much less walk... except then I had to. My ankle didn't "get better". In fact, it was probably in worse shape for the fact that I stood and put weight on it to get upstairs to a comfy chair instead of sitting where I was and getting it propped up and icing it right there in the stairwell. But in terms of immediate OMGOWICAN'TDEALWITHTHISPAIN? I was able to push it aside, so I could get to my feet and do what I had to in order to ultimately recover.
I couldn't keep doing that indefinitely for new injuries. I couldn't do that on a day when I'd already been through a lot.
That's exactly the sort of thing that Healing Surges represent. Granted, I couldn't get up and fight like a heroic D&D character on a twisted ankle... but neither could I do so on a perfectly healthy one, so that's beside the point.
The Moral Of The Story Is?
If you think about it enough, HP and Healing Surges as they work in 4th Edition make a lot more sense than HP alone did in previous editions. If you think about it too much, of course, you can run into the cases where things just don't add up... but it's a fantasy game fueled by imagination. Fantasy deals with things that are plausible, not things that are possible.
So just remember that HP do not equal Life Force or Structural Integrity Points. This is why a Halfling Fighter and a Goliath Fighter don't have drastically different amounts of them. They don't reflect the size of each proverbial dog in a given fight, but rather the size of the fight in each dog.