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10 Most Common Mistakes DMs and Players Make in 5e D&D

If you’re like me you’ve been playing D&D a long time and 5e is not your introduction to this wonderful game. And if you’re like me you haven’t read every single page of the PHB and DMG. You’re an experienced player, you know what’s what. You rely on your experience and looks stuff up when you need to (good luck finding it in the PHB index).

However, as I play with more and more new players I find that many of the rules I thought were the same in 5e as they were in previous editions are not exactly the same. Many are quite similar but because I hadn’t taken the time to look them up I was doing things incorrectly. That’s not to say these errors broke the game, but if I’m doing things in a way that is contrary to the actual Rules As Written (RAW) that may cause confusions and lead to arguments in real life. Better to get it right and share that knowledge with others who didn’t know.

So to help all those experienced players like me who haven’t read the rule books cover to cover, I’ve compiled a helpful list of common mistakes I’ve seen or done when running or playing 5e D&D. This isn’t an exhaustive list, but it covers the most gross violations and misconceptions. And to assure you that everything I say in the article below is correct, I’m even going to site page references from the PHB as applicable.

1) Surprise!

Repeat after me “There is no such thing as a surprise round in 5e.” Don’t believe me, look it up. The first round of combat can function differently than normal if some creatures (friendly or hostile) are surprised. This is usually based on who’s hidden and who’s not, but there are other factors. Don’t even get me started on the Ambuscade action Rangers get in the Unearthed Arcana article. That’ll just make your head hurt.

(PHB pg. #189)

2) Initiative

Two players and a monster all roll the same number on initiative. Who goes first? In previous editions ties were settled by the Dex modifier or Dex score. In 5e that’s not the case. When players get the same result on their initiative check, it’s up to them to decide amongst themselves who goes first. The Dex score, the Dex modifier, and even the number on the d20 are all irrelevant. They just talk it out and decide. Of course if they can’t decide then they can roll off or find some other way to settle the dispute. Likewise if a bunch of monsters get the same result the DM can decide what order they go in.

Now I remember reading somewhere that when the DM and players tie the players ALWAYS go ahead of monsters. I’ve scoured through the PHB and AL Players Guide and I can’t find that written anywhere. Maybe it was something that was in the D&D Next play test? In any case, I’ve been applying this rule since 5e was launched and it’s worked very well. If anyone knows where this “rule” came from, please let me know in the comments below.

(PHB pg. #189)

3) Movement

Movement has changed (for the better) in 5e D&D. You can now move throughout your turn. You can move, attack, move some more, attack some more, move again, attack again using your bonus action, and move even more. You’re no longer forced to do all your moving at the beginning or end of your turn. Break it up into 5 ft increments and use them when you need to. Just be sure you understand how opportunity attacks work (more on that below).

One other thing about movement is the Dash action. This replaced the double-move common in previous editions. Think of movement in 5e as a pool of steps. When you take the Dash action you get more steps added to your pool. So a Rogue can use their cunning action to Dash as a Bonus action (adding to their pool) and then use their action to Dash (adding to their pool again).

(PHB pg. #190)

4) Bonus Actions

Many players who came from 4e liken bonus actions to minor actions. Although they are similar, they are not the same.

  • You cannot downgrade your action or your move to take a second Bonus Action. You get one bonus action per round; that’s it.
  • Many bonus actions can only be taken when you do something specific with your action. For example, if you make a melee weapon attack with your action, you can then make one off-hand attack as a bonus action. You cannot make the off-hand attack if you do something else with your action, like Dodge or drink a potion.

(PHB pg. #189)

5) Opportunity Attacks

The 5 ft step or shift is no longer a thing in 5e. If you back away from an enemy, moving out of their threatened area then that enemy can take a free swing at you (what we like to call an opportunity attack). Once inside a monster’s threatened area (usually all squares adjacent to that enemy) you can move freely wherever you want as long as you remain within their reach. So if you’ve got the speed you can literally run circles around an enemy and they will not get an opportunity attack. Remember that in 5e each creature only gets one reaction so if they take an opportunity attack against you they won’t get one against your ally when he runs away. Unless the enemy goes between you and your ally, then you’ve got a problem.

In 5e fewer things provoke opportunity attacks than in previous editions. For example, if you stand up from prone, an adjacent enemy does not get an opportunity attack. And if you make a ranged attack, an adjacent enemy does not get an opportunity attack – however, you do have disadvantage on the attack roll.

(PHB pg. #195)

6) Concentration

Many spells require the spellcaster to maintain Concentration. These spells remain active until one of three things happens.

  1. The spellcaster casts a different spell that also requires Concentration. You can only have one Concentration spell active at a time. The new one trumps the old one.
  2. The spellcaster is required to make a Concentration saving throw and fails (more on that below).
  3. The spellcaster falls unconscious.

While a spellcaster has a Concentration spell in effect they CAN cast other spells; they just can’t cast another Concentration spell or the first one stops. So a Cleric can cast Bless in round 1 and then cast Sacred Flame every round after that.

If a spellcaster has a Concentration spell in effect and they take damage they must make a Concentration saving throw (which is a Constitution save). The DC is either 10 or half the damage taken. So unless a single attack deals 22 damage or more the DC is 10. If the spellcaster fails the save the spell stops. Remember that a save is required every time the spellcaster takes damage. So a spellcaster hit by a level 1 Magic Missile would have to make three separate saves.

Concentration works exactly the same way for monsters and PCs so keep that in mind when monsters cast spells that require Concentration.

(PHB pg. #203)

7) Casting Two Spells

Yes, you can cast two spells in the same round. The only restriction is that one of them MUST be a cantrip. So we often see Clerics cast Healing Word (level 1 spell, bonus action) and Sacred Flame (cantrip, action) in the same round. This is absolutely allowed.

(PHB pg. #202)

8) Delay / Readying an Action

In 4e if you weren’t ready or you didn’t like your spot in the initiative you could delay and jump back into the initiative wherever you wanted. That’s not a thing anymore. Now you can Ready an Action if you don’t know what to do or need to wait for an ally or monster to do something first. You can only ready one thing (action or move) and you must declare a specific trigger that determines when you can do that thing. Readying an Action counts as a reaction so you cannot take an opportunity attack when Readying an Action. An important note for spellcasters, if you ready a spell and don’t cast it (perhaps the trigger wasn’t met) you lose the spell. This is why spellcasters generally only ready cantrips.

[EDIT] Point of clarification. If you’re readying an action and the trigger hasn’t happened yet, you can chose to take an opportunity attack if something provokes one, but doing so counts as your reaction and the readied action is forfeit.

(PHB pg. #193)

9) Short Rest

In 5e a short rest takes 1 hour, not 5 minutes as it did in 4e. Most players realize the change, but I’m still getting the occasional player who thinks they can regain their powers and expend hit dice to heal when they rest for 5 minutes. Resting takes a lot longer in game and therefore isn’t as common as it used to be. If monsters are chasing you now is not the time to rest.

(PHB pg. #186)

10) Death Saves

This was a new mechanic introduced in 4e that carried over into 5e. There are a few important changes that people still get wrong.

  • Death saves are now made at the BEGINNING of your turn, not the end. So if you get that magical 20 you’re awake and can take your turn as normal.
  • If the result is 20 or higher you gain 1 hit point. You do not need to roll a natural 20 (although that works too). If you’re the recipient of a Bless spell or a Paladin’s Aura of Protection those bonuses to saving throws apply to the death save. So you may regain consciousness if a number other than a natural 20 appears on the d20 as long as the total after all modifiers is 20 or more.
    [EDIT] So I have fallen victim to the very thing I was writing about at the outset. I am falling back on the 4e rules about adding bonuses to saves to modify the 20 outcome. Since the time I posted this I have found a few official Q&As in which this was asked and answered by Jeremy Crawford. It has to be a natural 20.

(PHB pg. #197)

How many of the things I wrote about above are you guilty of violating. Be honest. Comment below and tell us which ones shocked or surprised you the most. I especially want to hear from people who have been playing since 5e was released who are only now realizing that they were doing it wrong. No judgement, I just want to know that I’m not the only one.


40 replies on “10 Most Common Mistakes DMs and Players Make in 5e D&D”

Another one I’m guilty of, as a DM, is forgetting Inspiration. Not that we use it “wrong” at our table… just that the players forget to specifically try to get it, and I often forget to give it out if they act in-line with their background traits. I’ve implemented an “Everybody gets a point of inspiration after a long rest” rule that has worked well to fix this a bit, though.

1) There is no specific thing called a “surprise round” anymore, but the exact function of a surprise round still exists in the game. If even one creature is surprised, they can’t take actions, move, or react in round 1 of the combat. In this scenario Round 1 = the surprise round, it just doesn’t happen to be *called* the surprise round.

5) The 5′ shift is gone, but don’t forget you can choose to use the disengage action to avoid opportunity attacks.

#10 bullet point 2 is wrong. The only way to get that 1 Hit Point is on a natural 20. Even if you roll a 21 with Bless it’s still only a normal ‘success’. 3 successes and you are ‘stable’ but have no HP. (i.e. still out cold but not dying)

I too am guilty of forgetting inspiration. Even though I have written the word in big letters on a card pinned inside my DM screen, I still manage to forget it.

More related to your article, I have a different reading for your point 7:
– you can cast a spell as a bonus action and a cantrip as a standard action
*or*
– you can cast a spell as a standard action and another as a reaction.

For instance, you can cast fireball and shield in the same turn.

OTOH, for people used to 3E, haste is back to its older self, it no longer gives you an additional spell per round.

I agree with Anthony my PHB states “Rolling 1 or 20. When you make a death saving throw and roll a 1 on the d20, it counts as two failures. If you roll a 20 on the d20, you regain 1 hit point.

As to where you are getting “that when the DM and players tie the players ALWAYS go ahead of monsters” I think you are getting that rule from the actual rule “the DM can decide the order if the tie is between a monster and a
player character”. What has happened is that most DM are nice and just decide to always let the players go first and because of that it somehow became the official rule.

As someone who house rules reflexively, imagine my surprise when I actually have NOT been house ruling, and simply been using the system as written. It’s a very weird feeling, let me tell you.

I could technically say I’ve been house ruling 10, but now that I think on it, the only time it would have come up, the player rolled a natural 20 ANYWAY, which makes it moot. Also, no. 8 has yet to come up in my AL games.

6) A reminder: readying a spell uses concentration, even if the spell doesn’t use concentration. So, a caster can’t ready a spell and maintain concentration on a different spell.

7) Also the cantrip limitation only applies to spells with bonus action as the casting time. Sorcerers with Quicken Spell can use that ability to cast twice with whatever spells that cost an action they have

There’s one thing not listed here I have a few players still trying to do all the time: flanking. It doesn’t exist anymore, but they keep on trying. But nope, those bad guys can just keep turning around.

The rule is if you cast a spell as a bonus action, you cannot cast another spell that turn unless it is a 1 action cantrip. This applies to Sorcerers using Quicken spell as much as it does to a Cleric using Healing Word.

I tend to forget #7, though I know that’s the rule.

#7 – should be turn, not round. Casting a spell as a reaction can occur on any turn and should be the exception to that rule like Arnaud mentioned.

#10 – I’m with the others on the second part of the death save, it changes the terminology. Roll a d20, if the result is… is how they reference the first part. Second part is if you roll a X on the d20. Not if the results is X, or X or higher/lower. That seems to be on purpose. You need a nat 20.

You should read the rogue assassin archetype, there is definitely a surprise round. also, Suprise is actually described in PHB #189 there is a whole section just for that !

Surprise is actually the first round of combat and those surprised can’t take their turn at all. those who are not can take their turn on their initiatives. so yeah there is surprise rounds in this edition as well. because as mentionned some of the archetype mainly rogues do use that to their advantages.

Nyke, actually, on point 7) you are wrong, I’m sorry to put it bluntly. When you use Quicken Spell your spell becomes a Bonus Action spell, and so it becomes tied to the rule stating that on the same turn you cast a spell as a Bonus Action you can only cast a Cantrip with the casting time of 1 action.

Nyke: Quicken speeds up the spell casting time to a Bonus Action, so it still counts as a Bonus Action spell. This means you can Fireball and Fire Bolt in the same turn, but not Fireball and then Fireball.

Regarding #7: Yes, one of the spells must be a cantrip, but you’ve neglected to mention that the other one must have a casting time of a bonus action. You can’t cast a cantrip and a levelled spell that requires an action on the same turn.

8) It’s a subtle distinction, but Readying and Action DOES NOT count as a reaction in an of itself – it allows you to perform the action you specified in response to the trigger you specified as a reaction. Thus, you can still make an opportunity attack after Readying an Action, but you cannot perform both the Readied Action AND make the opportunity attack.

Number 8 is also wrong. Readying an action only requires an action, not a reaction. You state a trigger when you ready an action. When the trigger happens, you can choose to use your reaction to complete your readied action. You can choose to use your reaction before the trigger though, or outright ignore the trigger and not go through with the action if you wish.

Any spells that were readied are of course, lost.

Is this deliberately ironic?

No only are 3 of the 10 in error, but you have neglected the most common mistake: believing an unseen target’s location is unknown without it taking the Hide action.

Also, your statement that “Readying an Action counts as a reaction so you cannot take an opportunity attack when Readying an Action” is not accurate. Readying takes an Action on your turn, and you can use your Reaction when the trigger occurs or ignore it. If a creature left your reach between the time you used the Ready Action on your turn but before your trigger occurs, you could use your Reaction to take an opportunity attack against them. You don’t forfeit your Reaction when you take the Ready Action. You still have one until your trigger occurs.

The correct rule for ties in initiative is not “Players go before monsters” but rather the DM decides who goes first. PHB, p189

Side note on #9 that had me baffled:

Long rest don’t replenish all hit dices. They replenish all Hit Points and up to half Hit Dices. (p.186)

Nyke, your response about Sorcerers with the Quicken Spell is not correct. The only thing that Quicken Spell provides is it give you the ability to cast a spell that normally would has a casting time of 1 action into a bonus action for casting (PHP p. 102).

Since it now only takes a bonus action to cast, the rest of the that spell casting rule now applies. That is you can only cast a cantrip with a casting time of 1 action (PHP p. 202). This is the only time you are able to “exchange” or change an action type from 1 action into a bonus action.

Quicken Spell does not give you the ability to cast two fireballs in 1 round it simply changes the casting time from 1 action casting time to a bonus action casting time. At that point, the casting time bonus action rule then applies.

For your point #10 about death saving throws, the PHB is actually very specific that you must roll a 20 on the d20 to regain one hit point. PHB pg. 197.

I appreciate you putting up a list, and most of them are correct, but there are a few mistakes in the common mistakes list.

2) Initiative

Now I remember reading somewhere that when the DM and players tie the players ALWAYS go ahead of monsters. I’ve scoured through the PHB and AL Players Guide and I can’t find that written anywhere. Maybe it was something that was in the D&D Next play test? In any case, I’ve been applying this rule since 5e was launched and it’s worked very well. If anyone knows where this “rule” came from, please let me know in the comments below.

“If a tie occurs, the GM decides the order among tied GM-controlled creatures, and the players decide the order among their tied characters. The GM can decide the order if the tie is between a monster and a player character. Optionally, the GM can have the tied characters and monsters each roll a d20 to determine the order, highest roll going first.”

6) Concentration

Remember that a save is required every time the spellcaster takes damage. So a spellcaster hit by a level 1 Magic Missile would have to make three separate saves.

“If you take damage from multiple sources, such as an arrow and a dragon’s breath, you make a separate saving throw for each source of damage.” Magic missile is one source of damage so no multiple saves from one spell.

7) Casting Two Spells

Yes, you can cast two spells in the same round. The only restriction is that one of them MUST be a cantrip. So we often see Clerics cast Healing Word (level 1 spell, bonus action) and Sacred Flame (cantrip, action) in the same round. This is absolutely allowed.

“A spell cast with a bonus action is especially swift. You must use a bonus action on your turn to cast the spell, provided that you haven’t already taken a bonus action this turn. You can’t cast another spell during the same turn, except for a cantrip with a casting time of 1 action.”

There is no limit in place until you decide to cast a spell with a casting time of one bonus action. That means Eldritch Knights can use Action Surge to double cast non-cantrip spells. Yes, if they cast a bonus action spell that cannot do that, but there’s no inherit rule that states you are always limited to one being a cantrip.

8) Delay / Readying an Action

Readying an Action counts as a reaction so you cannot take an opportunity attack when Readying an Action.

You can forgo your Ready to take an oppotunity attack. You can choose to ignore the trigger. “When the trigger occurs, you can either take your reaction right after the trigger finishes or ignore the trigger.” Now, you cannot take an opportunity attack if you’ve used your reaction already. Maybe that’s what you meant. Ready doesn’t mean you give up triggering opportunity attacks though.

10) Death Saves

You do not need to roll a natural 20 (although that works too). If you’re the recipient of a Bless spell or a Paladin’s Aura of Protection those bonuses to saving throws apply to the death save. So you may regain consciousness if a number other than a natural 20 appears on the d20 as long as the total after all modifiers is 20 or more.

“Roll a d20. If the roll is 10 or higher, you succeed. Otherwise, you fail. A success or failure has no effect by itself. On your third success, you become stable (see below). On your third failure, you die. The successes and failures don’t need to be consecutive; keep track of both until you collect three of a kind. The number of both is reset to zero when you regain any hit points or become stable.

Rolling 1 or 20. When you make a death saving throw and roll a 1 on the d20, it counts as two failures. If you roll a 20 on the d20, you regain 1 hit point.”

It’s pretty clear that you need to roll it on the d20 for those special conditions to apply. Now, what CAN apply is the Aura, Bless, Halfling luck, etc to the total result that determines a pass/fail. They just can’t give you the auto 20. It’s like crit success/failures on an attack roll.

Nyke is wrong about the Sorcerer casting, unfortunately. Quicken Spell changes the casting time of the spell to a bonus action for that turn, so the only other spell you can cast is still a cantrip. The only way to cast multiple non-cantrips in a turn is to have another action, like with the fighter’s Action Surge; and even then, using a bonus action spell means you can only do cantrips on those actions.

i had a player die at my table befor we realized that all fails on death saving throws go away once you get back up, they don’t stay all day like in 4e.

#10 is definitely incorrect. From the PHB:

“When you make a death saving throw and a 1 on the d20, it counts as two failures. If you roll a 20 on the d20, you regain 1 hit point.”

Also,

“If the roll is 10 or higher, you succeed….”

Rolling 20+ with modifiers is only a success, not a revival.

They say if you want to know the answer to a questions on the internet don’t ask the question because no one will answer, instead provide the wrong answer and numerous people will correct you. Now that was certainly not my intent, but as many people pointed out the second part of #10 was indeed wrong. I have since been provided with multiple references to the correct ruling including some Tweets and Q&As from folks at Wizards.

I was also not clear in #7 regarding reactions as many people pointed out. I have added an amendment.

I deliberately did not write anything about Stealth or being hidden. This is a topic that was discussed to death when 5e was first released and I didn’t want to go down that rabbit hole. So while I realize mistakes are commonly made when it comes to Stealth and being hidden I chose not to cover that in this post.

I want to thank everyone who commented here, on Facebook, on Reddit and on Twitter. This article did exactly what I’d hoped it would do and that’s generate discussion about rules that people misunderstand and get wrong. And as it turned out even I get them wrong sometimes too. Please continue to comment and provide your feedback. Through this kind of discussion we become better DMs and we can provide our players with the best possible play experience.

Maybe I am being stupid here but is being hit by 3 Magic missile only one source of damage?

And TIM there is a flanking option in the DMG if you are interested on page 251 and if you really want to make it interesting try facing DMG 252

What my group gets wrong or does not use is cover
DMG p251
COVER To determine whether a target has cover against an attack or other effect on a grid, choose a corner of the attacker’s space or the point of origin of an area of effect.
Then trace imaginary lines from that corner to every corner of any one square the target occupies. If one or two of those lines are blocked by an obstacle (including another creature), the target has half cover. If three or four of those lines are blocked but the attack can still reach the target (such as when the target is behind an arrow slit), the target has three-quarters cover.
PHB 196
A target with half cover has a +2 bonus to AC and Dexterity saving throws. A target has half cover if an obstacle blocks at least half o f its body. The obstacle
might be a low wall, a large piece o f furniture, a narrow tree trunk, or a creature, whether that creature is an enemy or a friend.
A target with three-quarters cover has a +5 bonus to AC and Dexterity saving throws.

The important thing here is “that creature is an enemy or a friend”

Re: Surprise, a corollary to the confusion is that some players still think that you can only take one action when you have surprise.

Re: Initiative, I think the “rule” that players go before monsters on a tie comes from the advice to DMs in the 4e DMG/DMG2.

Re: Readying an action, another thing some players are confused about is that, once you ready an action, you cannot move first before your readied action goes off. For instance, if you are standing by a door and say you are readying a melee attack against the first enemy that enters the room (anticipating that the enemy will enter through that door), if the enemy somehow enters the room other than through that door, and is out of your melee reach, you cannot move to the enemy and take your attack. You simply lose your action that round.

Another common mistake is that rolling a 1 on the die on a skill check is an automatic fail. It isn’t. Admittedly, it is very likely a fail, but if your modifier is high enough, you will succeed. A 1 on the die is only an automatic miss on an attack roll.

I have my players give each other inspiration because I never remember to do it either. They each have 2 poker chip markers (color coded) that they can give out for the session. I’m sure some players would abuse this, but it works for us.

I’m a little late to comment on this, but I just thought I’d add my 2 cents on how well I believe 5e was written, in regards to concentration.

Not only have others pointed out that magic missile is a single “source” of damage, but the spell actually specifies that all of the missiles hit simultaneously. So by the developers stating that “whenever the spell caster takes damage” they double specified that only 1 concentration check is made for this spell.

Scorching ray on the other hand requires separate attack rolls for each ray, differentiating the timing of the rays, as each is an individual attack. Ergo each connecting ray would require a concentration check.

@ Rico – While page 174 of the PHB does support your claim on natural 1s not being an automatic fail, and modifiers still coming into play, generally speaking, most DMs do follow this rule. Generally speaking, it works in the players advantage on the opposite end of the die. A check may have a DC higher than achieveable based on a characters stats, but a Natural 20 make the check a success regardless of your modifiers. I think every D&D player would agree that having a chance to “sneeze in the middle of picking the easiest lock and breaking the pick” is an acceptable risk for “having Tempus hear your roar, giving you the strength of 100 men, and you overpower the Giant, and you throw him off the cliff”

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