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.

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. The spellcaster is required to make a Concentration saving throw and fails (more on that below). 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.

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