Synchronize Roll

I’ve got two players in my campaign who are close friends in real life, but like to make characters that have tension between them. Think Star Lord and Rocket Raccoon. I like their strong character choices and want to be able to mechanically reinforce their role play decisions as a DM. The problem is that DnD doesn’t really have good rules for determining outcomes in this category of conflict. I’ve made a house rule to quickly test if two personalities can work together. Basically, both parties roll a D20 and if they get the same number, or close to the same number then they get the thing they want. If one player gets a high number and the other gets a low number, then the characters just aren’t on the same wavelength. I know that this isn’t a good rule. It conflicts with 5e design philosophy, is difficult to explain, and the math is wonky.

I wouldn’t ever want to see this rule in an official book. I might not even want to use this rule in my next game without serious tuning. However, it fits the game I’m running right now perfectly. The players like doing it. It fit’s the tone of the story I’m telling. And the longer I play with it I keep coming up with more and more interesting ways to use it to challenge the party. There is a school of thought that says you shouldn’t allow homebrew in your game. They don’t want you to ruin the “balanced” ruleset with whatever your made-up nonsense is. Well, they can play however they want, but my imbalanced rule is a lot of fun at my table and now I want to share it. Screw the guys who say that you should be afraid of game design!

Synchronize roll

How to do it

Identify two parties who are working for a common goal but have some conflict between them. Identify their goal and define the stakes of the conflict. What happens if they succeed? What happens if they fail? Set a difficulty for the roll that is equal to the range of numbers that the players must roll within (bigger range equals less challenging, smaller range equals more challenging). Each player rolls a D20 at the same time. If the two numbers are within the range then it’s a success, if not then failure.

How ranges correspond to difficulty

Get the same numbers is a critical success

Get within 3 numbers of each other is a hard but doable task

Get within 6 numbers is an easy task

*Don’t assign ranges larger than six because the math gets weird.



I’d like to be able to include skill and proficiency bonuses into the synchronize roll. However, those modifiers only work if you assume higher numbers are always better than lower numbers. For synchronize, if your friend rolls low, then it’s better for you to roll low than it is to roll high. A possible fix would be to let players add or subtract their modifiers but synchronize is already a little weird and complicated, so I don’t want to make that worse by forcing players to do subtraction. I could only allow the person who rolled lowest to add their modifiers to try to bump it up towards the higher number, but that feels like punishing a player for rolling high. At the end of the day, my players have fun without adding bonuses to their rolls so I’m fine leaving it as is.


Here is a bunch of examples of fun challenges that I think a synchronize roll does better than the help action, or some sort of contested roll. I’ve broken the examples up into three different premises: talking your way past a guard, trying to navigate or copilot a vehicle, and fighting over leadership roles. Then I’ve given a few specific examples of what different challenge ratings might look like within each of those premises.

BSing a Guard

you and your buddy are talking to a guard, roll to see if you can keep your stories straight


Random stop at the checkpoint. The guard is just trying to do his job and go home. Act naturally and you will be fine

Difficulty—Roll within 6 of each other

Success—The guard lets you pass

Failure—They become suspicious and wave some more guards over


You’ve done something to catch this guard’s attention. Now they are coming over here to talk to the two of you about it. Roll to see if you can keep your stories straight.

Difficulty— Roll within 3 of each other

Success—You give them the runaround. The guard is still suspicious but has better things to do than stand around talking to you all day.

Failure—“maybe we should go down to the station and talk some more about this.”


You both got caught at the scene of the crime and now the detective is pumping you for information.

Difficulty—Roll within 1 of each other

Success—You both keep your cool. They have nothing on you.

Failure—One of you cracks. Which one is it and what do you tell them?


one of you is piloting, the other is giving directions. Synchronize to see how well you are communicating


The weather is nice and neither of you is under pressure.

Difficulty—automatic success!

you get where you were going


Vision is obscured, or you don’t know the way well.

Difficulty—Roll within 5 of each

Success—you get where you were going

Failure—you get where you were going but add an extra day and random encounter to travel because you get lost or argue about directions


One (or both) of you is trying to make the rout more confusing.

Difficulty—Roll within 4 of each other

Success— You lose your tail or otherwise avoid detection, but it takes longer to get where you were going.

Failure—It still takes longer to get where you were going, but you aren’t fooling anybody


You are in danger or must otherwise drive recklessly.

Difficulty—Roll within 3 of each

Success—you avoid the danger

Failure—you are caught by whatever is chasing you. Roll for initiative!


Goblins are going to attack the town in 24 hours! The Village must work together to build defenses but some of the elders think they can do a better job leading the townsfolk and maybe the party should just mind their own business. (Party nominates one person to roll for the PC’s, GM rolls for the NPC’s)


The Elders don’t like where you are putting anything. They tell the villagers to move it basically as soon as you set it down.

Difficulty—Roll within 4 of each

Success— Their pettiness is frustrating, but manageable. Somehow you still manage to get along well enough to Finish all your preparations in time.

Failure—It’s impossible to work with these people! You spend more time forcing the peasants to move things back and forth than you do working. Not all the defenses are constructed in time

2)      DEFENSES

The elders are commanding a unit of peasant levies. The party can take on the main forces if the peasants can just protect your flank. The elders might have different ideas about you getting all the glory though.

Difficulty—Roll within 2 of each

Success—The peasants stay in formation and the plan goes off as intended

Failure—The peasants break formation and attack the main goblin force head on. You need to go rescue them now.

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