The DM fudging dice rolls behind the screen has always been a topic of debate. There are a lot of reason why a dungeon Master might fudge a roll but is it right or ethical?
There are so many reason why you might be tempted to fudge a roll behind your screen. I want to cover the most common ones from least important to the most critical reason you might be faced as a DM. There are lot of times when you want to cheat with your dice and these are just a few examples of when and not the only reason why.
To drive the story
There are times when your story needs that player to find the thing, and without the thing your story ends and leaves the players wondering where to go. A good example is having the hidden thing behind a magically locked door and they missed an important key to four rooms ago. You allow the rogue to try and pick the lock or the wizard to make an arcana check to see if the figure it out. Both of them fail the check, and you are now stuck. You end up lowering the DC value you had put in place to allow them to succeed and continue along the way. You may not have changed the roll but you have allowed the outcome to change.
Failure is a big part of the game and just as important as success. If success was the only outcome the players would soon become bored. Let them fail and provide something new. The ability to think your feet will help you with this. Have a plan B ready to go just in case the party fails something important.
The Power Player
You have that one power player who can bash your poor minions to bits and never gets hit due to a high Armour Class. To combat this you change your rolls to critical and add damage to your rolls. You are trying to make it a challenge for the power player. There are Dungeon Masters that use the constant hits and extra damage as a punishment to players who have min/max characters designed to beat certain types of creatures and with defeating the DM’s normal array of traps and bad guys. Changing dice rolls or having this player hit regardless of the roll is normal action for a frustrated DM.
Don’t change the rolls. Adjust the encounters and perhaps add a few custom beast that have resistance to certain power player weapons and abilities. Everyone has a weakness.
If you have an issue with a min/max player there is always a weakness to exploit without having to fudge your dice rolls. You can always change encounters up that make one of the other players shine. There is a difference between a DM who challenges you to your limits, and one that is actively trying to kill you.
Saving a Players life
This has to be the number one dice alternating scenario. You have that player who is down to 2 hit points and you roll a hit doing damage enough to start making the character begin the death saving roll cycle. It’s one of the most difficult situations to be put in. You are about to potential kill one of you players characters. Its heart pulling. That player maybe very attached to the character. You turn that hit into a miss to save the character.
Sometime characters die. Sometime the characters are a favorite of yours and the party. Sometimes a player made the mistake of naming his character Sean Bean setting into motion the eventful death that was sure to follow. Character death is part of the story and it happens. There is lots of information on how to treat character death so I won’t touch on it. It shapes the other characters and may create a whole story that didn’t exist before.
Those little plastic poly shaped objects are not just there for show, and give the players something to play with when it’s not their turn. They represent the random element that happens in life.
As an example: You’re driving down an icy road after stopping off to get your morning coffee. You decide to take the risk of trying to take a sip of that yummy and delicious wake up liquid. You make a DEX check to balance the coffee in your hand and fail. The coffee spills all over your lap and you need to make a CON save to handle the pain of hot coffee on your sensitive parts. You fail and lose control of the car on the icy road. You make another DEX with disadvantage because of the icy roads. Natural 20… yeah you are going to be fine, minus a few points of damage and your evening date plan ruined. All of those rolls have an impact on how you are molded as a character.
Those rolls you and your players make, create the story and define the outcome of events. When you change a roll you change the story and the possibilities of what could have been.
It’s easy to acquire the god complex as a DM but when does it stop being about how much you control and become more of the player’s story.
You already have total control without having to change rolls. You are in control of the encounters, the NPC’s, the Land & Sea, and the gods. What more do you need? Remember you are more a facilitator to the player’s story that they are in control of. They choose where they go and what they do. You can provide some interesting hooks to draw them into a story but it is really up to them.
I have my own opinion on dice. When designing encounters I careful think these out. I look at the party as a whole and challenge them according to their skills and limits. Never actively try to kill someone or teach them a lesson by changing die rolls. Use your imagination and be clever.
If you change one die roll you can change them all. So why use them? Just tell your players when they are hit and what damage they take.
Players will do stupid things, and you cannot control that. They know it’s risky and probably not a good idea but try it anyways. Let chance make the choice. Poor decisions have consequences and a new story is born from it.