Core Rules You Never Knew

5th edition is simpler than previous editions of D&D, but it still has considerable depth built into its ruleset. Even after playing for half a decade, there are niche rules that still catch me out from time to time. That’s what this post is all about.

This week, I’m mainly looking at Chapters 1 to 4 of the Player’s Handbook (henceforth, PH). I was originally going to cover Chapters 5 to 8 this week as well, but the post got . . . rather long. So you have that to look forward to.

Disclaimer: this post is about rules as written (or, occasionally, rules as intended). It’s your game! Feel free to ignore them if it works better for you that way. If I’ve made any howlers, let me know in the comments.

Chapter 1: Step-by-Step Characters

Always round down. (7)

Whenever you divide a number in the game, round down if you end up with a fraction, even if the fraction is one-half or greater.

There are only two specific exceptions that I’m aware of: hit dice recovery after a long rest (186) and spell slot recovery for wizards and Circle of the Land druids (115 and 68, respectively).

You are not meant to roll your ability scores until you’ve chosen your class and race. (12)

This is a bit nuts to be, and obviously it’s more of a guide then a rule, but Chapter 1 of the PH tells us to choose a race, then a class, and then determine ability scores.

It’s interesting design intent – your race and class should be more important to you than your ability scores – but I still think it’s worth rolling your stats first.  

Point buy is a variant rule. (13)

It is assumed that you determine your ability scores randomly using 4d6 drop lowest. Point buy, used at many tables, is technically an optional rule. If you don’t like 4d6 drop lowest, try my method, explained here.

You don’t need a long rest to level up. (15)

The rules are very vague about how levelling up actually happens.

A character who reaches a specified experience point total advances in capability. This advancement is called gaining a level. (PH 15)

Of course, it’s up to the DM as to when experience points are awarded, but no, you don’t need to rest to level up, nor do you gain the benefits of a rest if you level up. When you roll your Hit Dice, you are increasing your hit point maximum, not your current hit points.

When you level up, your hit point maximum always increases by at least 1. (15)

This was actually corrected in the errata. The original PH says this: ‘Each time you gain a level, you gain 1 additional Hit Die. Roll that Hit Die, add your Constitution modifier to the roll, and add the total to your hit point maximum.’ The errata clarifies that this total is a ‘minimum of 1’, even if you have a terrible Constitution and roll poorly.

You don’t have to roll your hit points. (15)

Alternatively, you can use the fixed value shown in your class entry, which is the average result of the die roll (rounded up).

Taking the average isn’t a variant – it’s a core rule. However, if you do roll, you can’t then take the fixed value if you roll poorly (or at least, that seems to be what the word ‘alternatively’ suggests).  

Chapter 2: Races

Mountain dwarves and high elves don’t exist in the Forgotten Realms. (20, 23)

OK, this is a bit pedantic, and it’s not really a ‘rule’ as such, but I’ve always thought it was an odd design decision given that Faerûn is the assumed setting for almost every 5e adventure module. Anyway: mountain dwarves and high elves are not a thing in the Forgotten Realms. Mountain dwarves are called shield dwarves and high elves are called moon elves or sun elves (two different subraces with the same mechanics). Stout halflings, similarly, are called stronghearts.

In the right conditions, a wood elf can hide in plain sight. (24)

This is confirmed in the Sage Advice Compendium. ‘It’s as if nature itself cloaks a wood elf from prying eyes – even eyes staring right at the elf!’ Of course, a Dexterity (Stealth) check is still required.

Similarly, a lightfoot halfling can hide even when an observer is nearby. (28)

Again, see Sage Advice.

There are only four common races. (33)

Dwarves, elves, humans, and halflings are common. Other races, like half-elves, tieflings, and gnomes, are more unusual and may provoke different reactions outside big cities.

Chapter 3: Classes

I have restricted myself to the core classes here. Including subclasses wouuld be considerably more work.

A barbarian’s rage ends early if it hasn’t made an attack or taken damage. (46)

By extension, a barbarian’s range ends early if the barbarian is incapacitated, paralysed, petrified, or stunned – unless, of course, they take damage. And this damage can come from an ally!  

A barbarian can (and probably should) wear armour. (46)

Unarmoured Defence is actually a bit of a trap.

While you are not wearing any armor, your Armor Class equals 10 + your Dexterity modifier + your Constitution modifier. You can use a shield and still gain this benefit.

This is very thematically appropriate, but a barbarian is still proficient in light and medium armour. Studded leather gives you an AC of 12 + Dex modifier and half-plate gives you an AC of 15 + Dex modifier. In other words, unless you have a combined Dex-Con modifier of 6 or higher, you are probably better off wearing armour. And if Stealth is important to you, a breastplate still provides an AC of up to 16.  

You don’t get to use Extra Attack on an opportunity attack. (46)

‘you can attack twice, instead of once, whenever you take the Attack action on your turn.’

An opportunity attack is a reaction taken on someone else’s turn. This applies to barbarians, fighters, and any other character that gains the Extra Attack feature.

A bard need not be a musician. (51)

Despite the flavour text, there’s nothing to say that a bard has to play music to use their powers.

Bardic Inspiration:

You can inspire others through stirring words or music

Song of Rest:

you can use soothing music or oration


you gain the ability to use musical notes or words of power

Even if they are using a musical instrument as a spellcasting focus, there is nothing to say that they must play the instrument. You just have to hold it. A spell component pouch is always an alternative, too.

Jack of all Trades applies to Initiative. (51)

Starting at 2nd level, you can add half your proficiency bonus, rounded down, to any ability check you make that doesn’t already include your proficiency bonus.

Initiative, as per PH 189, is an ability check. Enjoy the bonus!

Jack of Trades also applies to grapple checks. (51)

They are not attack rolls! They are ability checks. You get to add half your bonus if you are not proficient in Athletics already.

Preparing a new spell list takes time. (56)

This applies to clerics, druids, paladins, and wizards: the four classes that prepare spells. Preparing a new spell list requires ‘at least 1 minute per spell level for each spell on your list.’ It probably won’t come up in play, but hey, it’s a rule. (If you are playing as an artificer from Eberron: Rising from the Last War or Tasha’s Cauldron of Everything, this rule applies to you, too.)

A druid can wear armour or use shields made of metal. (65)

They just choose not to – much as a vegetarian is able to eat meat but chooses not to. Ultimately, the taboo is more about story than game mechanics, and it’s up to the DM and the group to decide what happens if a druid wears, say, scale mail (which they are technically proficient with).

Incidentally, if you’re wondering whether a druid can wear studded leather, the Sage Advice Compendium says, ‘a druid typically wears leather, studded leather, or hide armor,’ so I would take that as a ‘yes.’  

Using wild shape, a druid’s equipment can merge with it – but doesn’t have to. (64)

Equipment that merges with the form has no effect until you leave the form. So if you’re wearing a cloak of protection and use wild shape to turn into a bear, you lose the benefit of the cloak of protection if it merges into the bear form. Solution? Don’t merge the cloak! Yes, your bear is now wearing a cloak of protection like a superhero cape, but they get to keep the +1 bonus to saves and AC. Win.

(That said: it won’t always make sense for an animal to wear a magic item. The Dungeon Master’s Guide has a little more detail on this – p 140. Note that a druid’s equipment can be merged, dropped, or worn, too – not ‘held’. So weapons, wands, staffs, etc need to be dropped or merged, as these are not items that you ‘wear’.)    

Action Surge gives you an extra action, not a bonus action. (72)

This matters for fighters who are using two-weapon fighting, for example, as the off-hand attack is a bonus action.

A monk cannot make more than three attacks per turn until 5th level. (76)

It’s easy to get this wrong. Monks have two abilities that allow them to make extra attacks: Martial Arts, which lets you make an unarmed strike as a bonus action when you attack with an unarmed strike or a monk weapon on your turn, and flurry of blows, where you can spend a ki point to make two unarmed strikes as a bonus action. Here’s the problem: both of these abilities use your bonus action, and you only get one bonus action per turn. (This changes at 5th level when the monk gains Extra Attack.)

Divine Sense doesn’t go through walls. (82)

I’ve seen players try to use divine sense to detect the presence of evil enemies. But read the description:

Until the end of your next turn, you know the location of any celestial, fiend, or undead within 60 feet of you that is not behind total cover.

A paladin’s Divine Smite is capped at 6d8. (82)

And that’s against an undead or a fiend: against all other targets, it’s 5d8. This matters if the paladin is a high-level ‘sorcererdin’ or other multiclass combination. Even if you have access to 6th-level spell slots (and higher), the cap still applies. (Of course, if you crit, that’s another matter: roll all the dice twice!)

A paladin can lose their powers for breaking their oath. (82)

This might seem obvious, but every oath has its own tenets, and wilfully violating this oath can carry serious consequences:

If a paladin willfully violates his or her oath and shows no sign of repentance, the consequences can be more serious. At the DM’s discretion, an impenitent paladin might be forced to abandon this class and adopt another, or perhaps to take the Oathbreaker paladin option that appears in the Dungeon Master’s Guide.

Look at what some of these oaths ask of you. Some are very specific. For example, the Oath of Devotion clearly states, ‘Don’t lie or cheat’, ‘aid others’, and ‘do as much good as possible while causing the least amount of harm.’ Paladins are a powerful class, and with great power comes great responsibility.

A rogue can sneak attack on someone else’s turn. (94)

Once per turn, you can deal an extra 1d6 damage to one creature you hit with an attack if you have advantage on the attack roll.

Once per turn – |not once per round. So a reaction (eg, an opportunity attack or a readied action) is someone else’s turn, and you’re free to sneak attack again.

A grappled ally can still set up a sneak attack. (94)

You don’t need advantage on the attack roll if another enemy of the target is within 5 feet of it, that enemy isn’t incapacitated, and you don’t have disadvantage on the attack roll.

Note that you are also incapacitated if you are paralysed, petrified, stunned, or unconscious.

You can use only one Metamagic option on a spell. (99)

Unless otherwise noted. So: no extended, heightened, empowered spells.

A warlock doesn’t know their patron’s spell list automatically. (108)

Warlocks get access to an expanded spell list depending on their patron. However, unlike a cleric’s domain spells or the spells a paladin gains from their sacred oath, these spells aren’t known automatically.

Copying spells into a wizard’s spellbook costs time and money. (112)

This might seem obvious for experienced players, but new players might not realize how costly it can be for a wizard to learn new spells:

For each level of the spell, the process takes 2 hours and costs 50 gp.

So a 4th-level spell takes eight hours to copy and costs 200 gp in materials. At high levels, it could take a wizard days to copy up spells.

That’s it for this week. Next week: feats, equipment, multiclassing, and adventuring!

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