What to Do if You Forget a Rule in D&D 5e

There are a lot of rules for a DM to remember in Dungeons and Dragons. So many, in fact, that even the best DMs are sure to forget something. So what happens when you forget a rule or completely?

Mess up a ruling during a game? How can you correct your error without completely stopping the game? Here are some tips I have picked up over the years that just might help you out in a pinch!

If you forget or don’t know a rule during gameplay you should:

  • Make a ruling at the moment based on logic and look up the rule later
  • Always let the players roll something (when applicable)

If you realize you messed up a rule during gameplay you should:

  • Apologize, explain and correct the ruling immediately if the ruling would have changed the outcome of the situation drastically
  • Apologize and explain the rule for the future if the rule would not have changed the outcome

You should only pause gameplay to look up rules if it is absolutely imperative to the situation. For the most part, these tips should be enough to get you through any situation.

A Couple of House Rules…

For my games, I make sure to have a couple of house rules that help me focus on the story elements and not on a bunch of rules. Feel free to adopt these, they work well!

1.Players are responsible for knowing the rules of their Class, Race, and Spells

If players are unsure of a rule on their class or race (which I don’t know immediately) then they are responsible for looking it up outside of their turn. If they mess up a class or racial ability, I will not correct it, as they are responsible for these things. These are their characters, they should have the rules for them down.

2. No stopping the game to look up a rule that doesn’t matter

If I make a ruling that is incorrect, or I don’t know a rule and make an educated guess at a time when the ruling would not noticeably impact the game, players cannot stop the entire flow of the game just to look up or make me look up a rule. That’s just lame.

3. Trust I am doing the best that I can

Am I perfect? NOPE. Will I make mistakes. YEP. Do I mean to? Never. As long as your players trust you are doing your very best, they won’t have a problem with your rulings, even when they are wrong.

What to Do When You Don’t Know a Rule

There will be times when you don’t know a rule in Dungeons and Dragons. There are simply too many to memorize. In order to prepare for these situations, I like to know several key general rules that I can apply to most anything. Using these, I can make a logical ruling without having to know exactly how the rule goes.

Whatever you do, don’t hold up the game for several minutes trying to find a rule that really doesn’t matter. If it can wait, then make a note of it and look it up LATER. You will not ruin the game by ignoring a small rule, you WILL ruin a game by taking 10 minutes to find a rule.

Go with What Makes Sense

If the rule affects the players’ actions, such as moving through difficult terrain, attacking underwater (I have a whole post about Underwater Combat!) or position, just think through the situation logically and make the best ruling you can at the time. 

Would it make sense for a player to attack normally underwater? No, it wouldn’t, so, logically, there is probably a penalty for swinging an ax underwater. Give players disadvantage on attack rolls and explain that the ax is much more difficult to swing underwater.

Would it make sense in combat to have advantage against an enemy that is surrounded? Yes, it does. So give the players surrounding an enemy advantage on their attack rolls. 

Do what makes sense at the time and look up the actual rule later. You will be surprised how accurate you are most of the time!

There’s an App for That!

If you do need to look up a rule during gameplay, I suggest making sure you have the “CompleteReference” for Dungeons & Dragons app. This app makes it quick and easy to search for rules, spells, feats, racial abilities, and really anything else you might need to know at the moment. (You can find this app and many others in my post “10 Amazing Apps Every DM Needs”)

You don’t need to know all the rules, but you do need to be able to find them quickly. So either memorize where things are in the Player’s Handbook and DM’s Guide or download this free app. You can guess which is easier.

Have Players Roll Whenever it Makes Sense

If you are trying to figure out if you should allow a player to attempt something, always have the player roll so that the ultimate decision is left up to chance.

Say a player wants to climb a tree, but they are wearing full plate armor. Then, the logical thing to do would be to have them roll an Athletics check with disadvantage. Then if that player falls and lands on another player who is trying to catch them, the player on the ground would take 1d6 bludgeoning damage (plate armor is heavy!) unless they succeed on a dexterity/strength check (depending on the class).

This rule isn’t anywhere in the books, but it makes logical sense. Make a logical ruling, then have the players roll to see how it all turns out. I promise, no one argues with the dice.

Know Your DCs

When you are making rulings on the fly, it is important to know your DCs. Difficulty Challenge (DC) are how difficult a situation. This is the number players are rolling against, and you need to have a DC in mind BEFORE you ask players for a roll. Use this chart to determine what the DC should be:

Difficulty DC
Easy 5-10
Medium 11-15
Hard 16-20
Very Hard 21-25
Nearly Impossible 26-30

The Rule of Cool

If you aren’t sure if you should allow a player to do something, I have a simple rule I like to follow, it is called the Rule of Cool.

If what the player wants to do is character-driven and adds to the enjoyment of the game for everyone, then I allow the player to attempt it.

Some DMs would never do this, but I have found that, most often, the best memories come from following this rule and letting the players try some crazy stuff. Should I have, technically, allowed it? Probably not. But it was cool, everyone loved it, and we still talk about it. So you tell me if I made the right call.

If you are so afraid of making a ruling that isn’t “technically” correct, then you are missing the point of D&D. Lighten up and follow the Rule of Cool.

Remembering all of the rules and making correct rulings at critical moments is probably the most stressful aspect of DMing. At times, the technical rule makes all the difference, but, for the most part, just doing your best and making a ruling that makes sense is more important.

Remember, game flow is king. If at all possible, always keep the game flowing or you will lose your players’ attention. Fun and emersion always win against technicalities. 

Until next time,

May your game have advantage, my friends!

-Halfling Hannah


Pssst…if you liked this article, you might like some examples of rules I get wrong all the time

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