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Core Rulebook / Chapter 4: Skills

Skill Checks and Skill DCs

Source Core Rulebook pg. 234 4.0
When you’re actively using a skill, often by performing one of its actions, you might attempt a skill check: rolling a d20 and adding your skill modifier. To determine this modifier, add your ability modifier for the skill’s key ability, your proficiency bonus for the skill, and any other bonuses and penalties.

Skill modifier = modifier of the skill’s key ability score + proficiency bonus + other bonuses + penalties

When writing down the modifier on your character sheet, you should write down only the numbers that always apply—typically just your ability modifier and proficiency bonus at 1st level. At higher levels, you may wear or use items to improve your skills with item bonuses pretty much all the time; you should write those down, too.

The GM sets the DC of a skill check, using the guidelines in Chapter 10: Game Mastering. The most important DCs to remember are the five simple skill DCs below.

Simple Skill DCs

Task DifficultySimple DC
Untrained10
Trained15
Expert20
Master30
Legendary40

When someone or something tests your skill, they attempt a check against your skill DC, which is equal to 10 plus your skill modifier. A skill DC works like any other DC to determine the effect of an opposing creature’s skill action.

See page 444 in Chapter 9: Playing the Game for more information about modifiers, bonuses, and penalties.

Armor and Skills

Source Core Rulebook pg. 234 4.0
Some armor imposes a penalty on specific skill checks and DCs. If a creature is wearing armor that imparts a skill penalty, that penalty is applied to the creature’s Strength- and Dexterity-based skill checks and skill DCs, unless the action has the attack trait. Check penalties from armor are detailed on page 274 in Chapter 6: Equipment.

Secret Checks

Source Core Rulebook pg. 234 4.0
Sometimes you won’t know whether you succeed at a skill check. If an action has the secret trait, the GM rolls the check for you and informs you of the effect without revealing the result of the roll or the degree of success. The GM rolls secret checks when your knowledge about the outcome is imperfect, like when you’re searching for a hidden creature or object, attempting to deceive someone, translating a tricky bit of ancient text, or remembering some piece of lore. This way, you as the player don’t know things that your character wouldn’t. This rule is the default for actions with the secret trait, but the GM can choose not to use secret checks if they would rather some or all rolls be public.

Exploration and Downtime Activities

Source Core Rulebook pg. 234 4.0
Some skill activities have the exploration or downtime trait. Exploration activities usually take a minute or more, while downtime activities may take a day or more. They usually can’t be used during an encounter, though the GM might bend this restriction. If you’re not sure whether you have the time to use one of these activities, ask your GM.