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Archives of Nethys

Archives of Nethys

Pathfinder RPG (1st Edition) Pathfinder RPG (2nd Edition) Starfinder RPG

Rules Index | GM Screen | Player's Guide
GM Core / Chapter 1: Running the Game / Special Considerations

Adjudicating Rules

Source GM Core pg. 15 2.0
As Game Master, it falls on you to adjudicate the rules. This means you're making judgments and decisions about the rules, especially when their application is unclear. Roleplaying games encourage creativity, and however well crafted and well tested a set of rules is, players will always find situations that require interpretation and judgment by the GM. You need at least some familiarity with the rules to run a game well, but you don't need to be the foremost expert on the rules. You don't even need to know the most about the rules at your table to be a great GM! There's a key difference between “knowing” the rules and “adjudicating” the rules.

While GMing, strive to make quick, fair, and consistent rulings. Your rulings should encourage your group to work together to interpret the rules and be creative with their characters' decisions and actions. If your group is satisfied with the interpretation, you've made the right adjudication!

The Basics

Source GM Core pg. 15 2.0
The following are some basic guidelines for adjudicating rules in play—these are the same principles that Pathfinder's game rules are based on. You might want to keep printouts of these guidelines and the DC guidelines for quick reference.
  • If you don't know how long a quick task takes, go with 1 action, or 2 actions if a character shouldn't be able to perform it three times per round.
  • If you're not sure what action a task uses, look for the most similar basic action. If you don't find one, make up an undefined action and add any necessary traits (usually attack, concentrate, manipulate, or move).
  • When two sides are opposed, have one roll against the other's DC. Don't have both sides roll (initiative is the exception to this rule). The character who rolls is usually the one acting (except in the case of saving throws).
  • If an effect raises or lowers chances of success, grant a +1 circumstance bonus or a –1 circumstance penalty.
  • If you're not sure how difficult a significant challenge should be, use the DC for the party's level.
  • If you're making up an effect, creatures should be incapacitated or killed on only a critical success (or for a saving throw, on a critical failure).
  • If you don't know what check to use, pick the most appropriate skill. If no other skill applies to a check to Recall Knowledge, use an appropriate Lore skill (usually at an untrained proficiency rank).
  • Use the characters' daily preparations as the time to reset anything that lasts roughly a day.
  • When a character accomplishes something noteworthy that doesn't have rules for XP, award them XP for an accomplishment (10 to 30).
  • When the PCs fail at a task, look for a way they might fail forward, meaning the story moves forward with a negative consequence rather than the failure halting progress entirely

Consistency and Fairness

Source GM Core pg. 15 2.0
As an arbiter of the rules and the person who's setting the scene for the action, it's in your best interest to appear fair at all times. Your main defense against appearing unfair is consistency in your rulings.

Achieving consistency is as easy as explaining why you're ruling a certain way and comparing this ruling to past rulings you've made in a way that makes sense to your players. For example, you might say something like “When Torben swung from the chandelier and attacked the air elemental, I required an Athletics check as part of the action and gave a +1 circumstance bonus to the attack roll. Hanging from the rope bridge to attack the giant bat sounds similar, so why don't you roll an Athletics check.” Do this any time it's applicable when you make a ruling, but don't feel compelled to do so for truly new rulings.

Through the course of playing, your previous rulings will form a set of shared preferences and an understanding between you and your group—or even become formalized house rules. Over time, your players will think about these examples when planning their actions, which can improve consistency during play.

Looking Up Rules

Source GM Core pg. 16 2.0
Remember that keeping your game moving is more important than being 100% correct. At the same time, it’s perfectly acceptable to refer to the rules during a session. However, you don’t have to do this alone. If you’re leafing through a book or searching an electronic reference, your players are idle. There are a few techniques that make these intervals more palatable for the players. Letting them know that you’re looking something up might prompt some players to also read the rule. This can increase the chances of collaboration and sets expectations for the length of the pause. Alerting your players that you’re going to take a minute and read the rules also lets them know that it’s a good time to tend to away-from-the-table tasks like refilling a drink.

Listen to the Players

Source GM Core pg. 16 2.0
The friends around your game table are perhaps your best tool for achieving quick, fair, and consistent rulings. Sharing the task of remembering the rules makes rules discussions collaborative rather than combative, greatly increases the chances of accurate and comprehensive recall of the written rules and your own past rulings, and is true to the shared storytelling spirit of Pathfinder.

Asking if anyone knows how a specific rule rewards those players who have spent time mastering the rules and involves more people in the discussion. It signals to other players that you are willing to hear opinions before making a ruling, and it builds a more collaborative environment. In addition, for groups with access to a large number of sourcebooks or rules resources, you can ask different players to examine separate sources. This can greatly increase the speed and accuracy of a group's rulings.

Approaching the rules as a group problem also means that you should never trivialize player concerns about a rule. You must also think about each player and assess how important the rules actually are to them. Remember, though—while rules recall is a group challenge, making the final decision on the rules interpretation and getting the session moving again falls to you.

Make the Call

Source GM Core pg. 16 2.0
Though all the above are great practices for making good rulings, often the best ruling is the one that keeps the game moving. Avoid getting so bogged down that it takes you several minutes to decide what ruling you'll proceed with. Take what's close enough and keep playing. If necessary, you can tell your group “This is how we're playing it now, but we can have more discussion between sessions.” This gets you back in the action, puts a clear stamp on the fact that this is your decision in the moment, and empowers your players with permission to express their opinions on the ruling at a later time. When in doubt, rule in favor of the player's request, and then review the situation later.

The best time to really go in-depth, possibly putting the group on a short break, is when a situation is life-or-death or has major consequences in a character's story.

Take Time for Review

Source GM Core pg. 16 2.0
When you make a decision you’re not sure about, look back over it at the end of a session or between sessions. You might change your mind—there’s nothing wrong with that! If you change or clarify your original ruling, inform your players before the next session. No one likes being surprised by a rule change. Even better, include them in a rules conversation just like you might during a session. The guidance on discussing rules with your players still applies between sessions. Unlike at-the-table rules discussions, there’s also much more time in these situations to read existing official rulings or sources.

Saying “Yes, But”

Source GM Core pg. 16 2.0
Some of the most memorable moments come from situations that inherently call for a rules interpretation, like when a player wants to do something creative using the environment. The variety of these situations is limited only by the imagination of your players. It's usually better to say “yes” than “no,” within reason. For example, imagine a player wants to do something borderline nonsensical like grabbing a spider and squeezing it to force it to use its web attack. But what about a player who wants to use a fire spell to deliberately ignite a barrel of oil? Surely that should have some effect!

This is where you can use a variant of the well-known improv “Yes, and,” technique: you can say “Yes, but.” With “Yes, but,” you allow the player's creative idea, but tie it into the world and the game rules via some sort of additional consequences, potentially adding the uncertainty of an additional roll. Here are some simple ways you might implement this tool:
  • Get a fleeting benefit without a roll. Example: dip a sword into a burning brazier to add 1 fire damage on the next attack against a troll.
  • Require a check, then apply a circumstance bonus to the PC's action. Example: swing from a chandelier above a foe.
  • Require a check, then apply a circumstance penalty or condition to a foe. Example: throw a barrel over a monster's head.
  • Require an attack roll or skill check to deal minor damage and gain another benefit. Examples: jump from a higher elevation down onto a foe for a small amount of damage, potentially knocking the foe prone; throw sand in an opponent's eyes.
  • Require a directed attack against an object, then allow foes to attempt saving throws against the object's effect at a DC you choose. Example: cast an ignition spell at a barrel of explosives.

Another powerful tool you can use to help you say “Yes, but” when you're unsure of the game impact is to allow the idea to work just this once, letting your players know that this is part of your decision. For instance, maybe you think a PC's attempt to Grapple a spider to aim its web attack at another foe is so fun you have to let them do it, but you're worried that the effect would be so powerful that the PCs would just carry around a spider to shoot webs for the rest of the campaign. By making it a one-time effect, you can have fun but don't have to worry about whether you're setting a disruptive precedent for later on.

House Rules

Source GM Core pg. 17 2.0
You and your players will inevitably come across a rule you disagree with or that runs counter to the theme of your game. You might even decide to add a specific rule to an area not covered by the written rules. Collectively, these rulings, changes, and additions are known as house rules. It's a good idea to record them in a place where the group can easily access and refer to them, and where a potential new player could find them. Such record-keeping is a great thing to delegate to a player!

The best rule of thumb in these situations is to be slow to change the written rules and quick to revert a problematic ruling or house rule. The simple reason for this is that sticking to the written rules is the easiest way to remain fair and consistent. However, the more you learn your group's play style, the more often you'll find times where you and your group feel it's correct to institute a house rule of some sort.