Should players know other creatures' HP? How do you deal with players not knowing the opponent's HP if not?

Question

I recently started playing D&D, and I was wondering about this.
I know it is up to the DM to choose whether or not players know enemies' remaining HP in combat: is it recommended to do so?

Instinctively, I would like to describe the visual effects of damage rather than telling the remaining HP for immersion, but that comes with a few problems.
For example, for a spell like power word: kill that can only activate when the foe has 100 HP or less, how do you deal with it?

First of all, based on your personal experience, what would be your recommendation for telling HPs of monsters or not to players?
If your recommendation is not to do it, how do you deal with all these meta-knowledge issues in-game?

Answer 1

The DMG section on running combat (p.247-248) has this to say:

Most DMs track damage in secret so that their players don't know how many hit points a monster has remaining. Whether you choose to be secretive or not is up to you.

Players often ask how hurt a monster looks. Don't ever feel as though you need to reveal exact hit points, but if a monster is below half its hit point maximum, it's fair to say that it has visible wounds and appears beaten down. You can describe a monster taken to half its hit points as bloodied, giving the players a sense of progress in a fight against a tough opponent, and helping them judge when to use their most powerful spells and abilities.

And since the Fighter's Battlemaster has a class feature (Know Your Enemy) that can tell you their HP in a very vague way, whether they have more or less than you do, it seems clear that the game at least expects HP to be secret information, while allowing that some DMs may decide not to hide it.

Most DMs, including me, give some kind of general indication of how much HP a monster has left using general terms like the "bloodied" reference above, which originates from 4th edition using that term to mean "below half health" (a good idea used -- perhaps overused -- in 4e to trigger a dramatic difficulty or style change in the fight). Many DMs describe being above half health as "unhurt" or "barely injured", below 50% as "hurt" or "has taken a few hits", and then at very low HP, perhaps 10%, phrases like "in really bad shape" or "barely standing" are common. There's usually nothing more clear than those, though, and definitely nothing numeric.

At my table, terms like "barely standing" are usually code to let the players know that the creature has only a handful of HP left; they can expect to take out the monster with a single hit of a basic weapon attack or cantrip. I'm letting them know they don't need to expend any resources on finishing off that target. Once in a while when an attack just barely fails to drop a monster I'll say something like "Ohhh! He's got two hit points left!" or "He survives that hit with one HP!" just to ramp up the tension. (But depending on the hit, I'm just as likely to ignore the last couple HP -- it's dramatic and fun to have a monster get finished off with a huge crit or incinerated by a fireball, so I have no problem with fudging in favor of the players there.)

I personally have never seen a problem with the metagame implications of Power Word: Kill, sleep, and similar spells and effects that depend on specific HP totals. Yes, there's a tactical decision to make there. Do you throw the spell now, or hold back and deal some more damage first? If you throw it too early, you waste the spell on a creature too strong for it. If you wait too long, you waste some of the spell's potential output, possibly taking more damage than you had to.

But that is, as they say, a feature, not a bug. Using those kind of spells is something of a gamble, and that's one of the balancing factors to them. I don't think you should be able to use spells like that with absolute certainty that they'll work. There's no save, so you have more control than you would otherwise, but it's never a sure thing.

Answer 2

In general I would advise against letting players know numerically how many hit points any NPC or even other members of their party have.

I've edited this to remove a section detailing the Bloodied condition as that is explained by another user. I have some additional suggestions below.

Another method is to expand the Search combat action to enable players to make a check (perhaps Medicine, Perception, or Insight) to gain information on the enemies stamina level, possibly this would be contested by the creatures Deception if you felt it was making an effort to hide its status. Personally, I would still never give numerical information but a roll of maybe 10+ could be rewarded with a decent description of visible/emotional wear and tear depending on the check that was made. The more time they had before combat to visually study them or prior research could let them pick up on smaller details (mechanically just adjusting the DC for various levels of information gained).

I also think players are within rights to take notes on how much damage their enemies could sustain before dying through the campaign. If similar enemies or recurrent villains appear again and again, that can be the great source of information for these sorts of decisions. Provided that information isn't directly vocalised in character. I think it's great for engagement and player agency. Different DMs may want to encourage or discourage that but personally I think it's a great analogue for characters assessing and learning from their encounters, especially if it fits with PC traits.

For spells or effects like Power Word Kill that you mentioned, I see no need to make any exceptions. The player chooses to attempt the casting, if the target has more than 100 HP, the spell simply fails. I consider this a research challenge ahead of the encounter for the player to ascertain how tough a specific enemy might be combined with an in-combat assessment of risk whether or not they want to cast it.

Sleep is a similar effect where you are effectively gambling on your assessment of the NPCs present and what you roll for the spell as to how impactful it will be. I don't think many players would expect to know the HP of everyone in range for that so they can optimise the effectiveness of that spell. I think that logic applies to the more powerful spells too.

Remember that these sorts of effects don't require you to tell the players what HP the enemies had, you just say they did or didn't die. Or in the case of Sleep, who fell asleep once you've done the calculations behind the screen. Hence this shouldn't conflict or otherwise cause meta-gaming problems.

If you never mention numerical HP in your games that should make it very difficult for your players to meta-game in that way. If players making notes start verbally sharing all how much HP they think a monster has numerically or using excessively detailed comments to the party during combat it could be time to have a word with them.

Answer 3

Normally not.

One reason to disclose is that since some DMs (for various reasons) set or alter the number of hit points on the fly instead of committing to the number ahead of time, and some (not all!) player groups dislike that, disclosing and tracking hp publically can be a way for them to know for sure that you aren't doing that.

Also, tracking hp publically can be a way to delegate work, so you all together can keep the game running. This can be great, I do it. Just as long as it doesn't come at the expense of engagement in the game.♥