English is not my native language, and I am translating D&D adventures for my players.
The D&D House Style Guide says:
Avoid referring to points of damage. For example, write, “The spell deals 10 fire damage,” not “The spell deals 10 points of fire damage.”
Would it be problematic to use such a phrase? Why should we avoid mentioning word “points”? And does it sound right in English colloquial?
The text you've highlighted is found in the paragraph introduced with the following :
The following style rules apply to the tabletop roleplaying game and to products based on it. When it comes to familiarizing yourself with the game’s terms and customs of wording, there is no substitute for reading the rules of the game themselves.
This whole section explains the rules of formatting, word capitalization and such that are used for official rules. The objective is to give guidelines for wording and formatting homebrew content, in order to make it more streamlined with official content and easier to compare to other content.
The section you mention is meant to tell that in the regular wording of official content, the term "point of damage" isn't the usual wording, so to stay close to the official wording, it's better to avoid it.
Do note that those are only guidelines for making homebrew content. They're not hard rules on how to make content, but only tips and tricks to make it better.
As to why this specific style rule of not using "point of damage", I couldn't find any interview, or other such public explanation for this style choice. Without actual insight from the people who decided on those rules we can only speculate.
With that said, as said in comments, using the term "points of damage" sounds perfectly correct, and might actually sound better once translated, depending on the target language. After all, those guidelines are made for english rules, so we cannot expect them to work as intended, however it was intended, in other languages.
Here is the definition of damage in the PHB (and basic rules):
Whenever a creature takes damage, that damage is subtracted from its hit points.
That's really the only definition of damage that's ever given. Damage is only ever defined as a number subtracted from hit points. Special cases are covered elsewhere, e.g. taking more damage than you have hit points, taking 0 damage, etc., but these all build on this simple one-sentence definition. In particular, there are no "points of damage" involved. As far as I know, such a term is never defined anywhere in the rules. The general guideline for terms that are not given a specific definition within the rules is to use the plain English definition. However, "damage point" doesn't have a plain English definition. When you fall and skin your knee, you don't say that your knee took 3 points of slashing damage. So, there is neither a rules definition nor a plain English definition for "points of damage".
So when the style guide says to "avoid referring to points of damage," all it it's really saying is "don't use a term that has no definition," which I think is a pretty reasonable and logical guideline. As to why the designers chose not to define damage in terms of "damage points", beyond observing that we have all got along perfectly well for years without such a definition, anything more would be pure speculation.
Regarding whether phrases like "The spell deals 10 fire damage" sound "right" in colloquial English, the answer is trivially no. Neither does "The spell deals 10 points of fire damage". If you said either of these outside of a context where damage numbers/points were explicitly defined in some way, they would sound like nonsense, or possibly they would be interpreted as a joke referencing the lack of such a definition. In real life, damage is almost never reduced to a number in this way (unless you're talking about the number of dollars you have to pay to fix it). So, when translating the rules to another language, my recommendation would be to find the translation of the definition of damage that I quoted above, and adjust your phrasing to be consistent with that definition. If that definition uses your language's equivalent of "points of damage", then go ahead and use that for your own writing in that language.
Including the words "points of" doesn't change the meaning of the rules, so it should be fine.
If you were attempting to publish a D&D adventure, then yes it would be problematic -- the problem would be that the people at WotC would want you to follow the style guide.
But you've written:
I am translating DnD adventures for my players.
and if your players don't object (and they almost certainly won't even notice) then this will not be problematic.
Would it be problematic to use such a phrase?
For your purpose of translation, no, there are no problems if you don't follow this point of the style guide. I'd list the problems, but there are none. Even if you publish your work, you need to consider your target language, and can't blindly apply the English style guide to it.
Why should we avoid mentioning word “points”?
Because style guide says so. Because you may want to sound more "5e" (see below). These apply only if you (the group) are aware of the recommendation, and then choose to care. It is your choice.
And does it sound right in English colloquial?
Using "points of" sounds right. Not having the unit of damage there, on the other hand, may actually sound a bit off to some people. "10 damage", what damage?
Even in the context of role playing games, the question remains, because some games do use "points of damage". Speculatively, this may be because in some games, there can be multiple kinds of damage, such as ability score damage. DnD 5e specifically restricts damage to current hit points, everything else is expressed differently, such as gaining levels of exhaustion, or having maximum hit points or ability score reduced (example: Shadow).
So "10 damage" is the 5e specific way of saying this. It's your choice if you want to talk in this 5e specific way (which may feel more special to some players) or in a more generic way (which may feel more inclusive to some players). My personal recommendation would be to just say it the way it happens to roll off your tongue, and let it sort itself out naturally.
Adding 'points of' is redundant in the context of a game that represents damage in standardized discrete units.
In standard English, damage is an uncountable noun. "The car crash caused a lot of damage" is fine, but if you want to talk about a specific amount, you have to specify what the unit is. "The crash caused $20,000 worth of damage" is perfectly comprehensible; "The crash caused 20,000 damage" makes no sense in standard English, as there's no presumed unit of 'damage'.*
In older editions of D&D, it was common to say "points of damage", because 'damage' was being used in the standard English way and required some unit specifier.
However, at this point, we've all been playing games that use damage points (or some similar thing) for many years. It's normal for games (whether tabletop, board game, or video game) to specify "5 damage" without having to qualify it -- it's understood what we mean by that. So it's no longer necessary to use the old "points of damage" phrasing in the context of a tabletop game suppliment.
Technically, there's nothing wrong with saying 'points of'; that's why this is a style choice, not a grammar rule. But skipping that phrase saves a few words and makes the rules read a bit more cleanly, and a style guide is all about providing a consistent experience with a given product line.
*This is common for other uncountables. You can have water, and you can have a liter of water, but you can't have 4 water. 4 whats of water? Bottles? Gallons? Tanker trucks?
It is not unusual or problematic in spoken discourse to refer to damage as "points of damage", even if that is not a defined game term (unsurpisingly so, as the Style Guide tells the writers not to use that term).
Health is measured in hit points. It is only natural to think of damage as points, then, too. Indeed, older editions of the game used the term, for example on page 9 of the original 1e PHB, it says
Thus, if a hit would normally score 1-6 points of damage upon the opponent [...]
So there certainly is usage precedent, and I doubt anyone would have difficulty understanding you, if you used the term. It does not sound wrong. No problem.
When it comes to writing, the question is, as in all writing, who your audience is. You are translating only for your players, so it does not really matter much, as long as all of you understand what is meant.
If however you would want to self-publish an adventure or setting book for general consumption, then you should aim to stick as close to the writer's guidance and precendent of the published, official books as possible. This will both make it easier for your audience to understand your work, and it will look more professional.
Lastly, if you are working on a book to be publishded for D&D by WotC, then it would obviously be problematic if you did not care for the written writers guidelines you are supposed to follow. You would cause extra work and cost for the editors. This would not look unprofessional in the end, because someone would have to fix it, but it would be unprofessional.
It clearly promotes consistency to give guidance either way so you don't end up saying 10 damage on one page, and 10 points of damage on another. Note that the guidance predates the actual rules books, so the absence of the term is a result of the guidance. If the guidance would have advised to use "points of damage" instead, than all the rules would be written that way now. Leaving out the extra words is shorter, and can help to conserve a bit of valuable real estate in the printed books and in stat blocks, where space is often tight. But we do not know what the design reason for the guidance were.
