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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
Chapter 8: Playing the Game

Checks

Source Player Core pg. 400 2.0
When success isn't certain—whether you're swinging a sword at a foul beast, attempting to leap across a chasm, or straining to remember the name of the earl's second cousin at a soiree—you'll attempt a check.

All types of checks, from skill checks to attack rolls to saving throws, follow these basic steps.
  • Roll a d20 and identify the modifiers, bonuses, and penalties that apply.
  • Calculate the result.
  • Compare to the DC.
  • Determine the degree of success and the effect.
Checks and Difficulty Classes (DC) both come in many forms. When you swing your sword at that foul beast, you make an attack roll against its Armor Class, which is the DC to hit another creature. As you try to leap across that chasm, you'll attempt an Athletics skill check with a DC based on the distance you're trying to jump. When calling to mind the name of the earl's second cousin, you attempt a check to Recall Knowledge. You might use either the Society skill or a Lore skill you have that's relevant to the task, and the DC depends on how common the knowledge of the cousin's name might be, or possibly how many drinks your character had when they were introduced to the cousin the night before.

No matter the details, for any check you must roll the d20 and achieve a result equal to or greater than the DC to succeed. Each of these steps is explained below.

Step 1: Roll D20

Source Player Core pg. 400 2.0
Start by rolling your d20. You'll then identify all the relevant modifiers, bonuses, and penalties that apply. A modifier can be either positive or negative, but a bonus is always positive, and a penalty is always negative. The sum of all the modifiers, bonuses, and penalties you apply to the d20 roll is called your total modifier for that statistic.

Attribute Modifier

Source Player Core pg. 400 2.0
Nearly all checks allow you to add an attribute modifier to the roll. Attribute modifiers represent your raw capability and are described on page 19. Exactly which attribute modifier you use is determined by what you're trying to accomplish. Usually, a sword swing applies your Strength modifier, whereas remembering the name of the earl's cousin uses your Intelligence modifier.

Bonuses

Source Player Core pg. 400 2.0
When attempting a check that involves something you have some training in, you will also add your proficiency bonus. This bonus depends on your proficiency rank: untrained, trained, expert, master, or legendary. If you're untrained, your bonus is +0—you must rely on raw talent and any bonuses from the situation. Otherwise, the bonus equals your character's level plus a certain amount depending on your rank. If your proficiency rank is trained, this bonus is equal to your level + 2, and higher proficiency ranks further increase the amount you add to your level.

Proficiency Bonus

Proficiency RankProficiency Bonus
Untrained0
TrainedYour level + 2
ExpertYour level + 4
MasterYour level + 6
LegendaryYour level + 8

There are three other types of bonus that frequently appear: circumstance bonuses, item bonuses, and status bonuses. If you have different types of bonuses that would apply to the same roll, you'll add them all. But if you have multiple bonuses of the same type, you can use only the highest bonus on a given roll—they aren't cumulative. For instance, if you have both a proficiency bonus and an item bonus, you add both to your d20 result, but if you have two item bonuses, you add only the higher of the two.

Circumstance bonuses involve the situation you find yourself in when attempting a check. For instance, using Raise a Shield with a buckler grants you a +1 circumstance bonus to AC. Being behind cover grants you a +2 circumstance bonus to AC.

Item bonuses are granted by some item that you are wearing or using, either mundane or magical. For example, armor gives you an item bonus to AC, while an expanded alchemist's toolkit grants you an item bonus to Crafting checks when making alchemical items.

Status bonuses typically come from spells, other magical effects, or something applying a helpful, often temporary, condition to you. For instance, the 3rd-rank heroism spell grants a +1 status bonus to attack rolls, Perception checks, saving throws, and skill checks.

Penalties

Source Player Core pg. 400 2.0
Penalties work very much like bonuses. You can have circumstance penalties, status penalties, and sometimes even item penalties. Like bonuses of the same type, you take only the worst all of various penalties of a given type. However, you can apply both a bonus and a penalty of the same type on a single roll. For example, if you had a +1 status bonus from a heroism spell but a –2 status penalty from the sickened condition, you'd apply them both to your roll—so heroism still helps even though you're feeling unwell.

Unlike bonuses, penalties can also be untyped, in which case they won't be classified as “circumstance,” “item,” or “status.” Unlike other penalties, you always add all your untyped penalties together rather than simply taking the worst one. For instance, when you use attack actions, you incur a multiple attack penalty on each attack you make on your turn after the first attack of the turn, and when you attack a target that's beyond your weapon's normal range increment, you incur a range penalty on the attack. Because these are both untyped penalties, if you make multiple attacks at a faraway target, you'd apply both the multiple attack penalty and the range penalty to your roll.

Once you've identified all your various modifiers, bonuses, and penalties, you move on to the next step.

Step 2: Calculate Result

Source Player Core pg. 401 2.0
This step is simple. Add up all the various modifiers, bonuses, and penalties you identified in Step 1—this is your total modifier. Next add that to the number that came up on your d20 roll. This total is your check result.

Step 3: Compare to DC

Source Player Core pg. 401 2.0
Whenever you attempt a check, you compare your result against the Difficulty Class (DC) of the check. Your check succeeds if it's equal to or greater than the DC. If you roll anything less than the DC, you fail.

Sometimes you'll know the DC and make the comparison yourself. Other times, you might not know the DC right away. Swimming across a river would require an Athletics check, but it doesn't have a specified DC—so how will you know if you succeed or fail? You call out your result to the GM and they'll let you know if it's a success, failure, or otherwise. While you might learn the exact DC through trial and error, DCs sometimes change, so asking the GM whether a check is successful is best.

Getting a DC from a Modifier

Source Player Core pg. 401 2.0
When someone attempts a check against you, you might need to defend with one of your statistics that’s normally a modifier, such as your “Reflex DC.” Rather than rolling a check of your own, you need to generate a fixed DC based on your modifier. Your DC for a given statistic is 10 + the total modifier for that statistic. So if you have a +4 Reflex save, your Reflex DC is 14.

Step 4: Degree of Success

Source Player Core pg. 401 2.0
Many times, it's important to determine not only if you succeed or fail, but also how spectacularly you succeed or fail. Exceptional results—either good or bad—can cause you to critically succeed or critically fail at a check.

You critically succeed when the check's result meets or exceeds the DC by 10 or more. If the check is an attack roll, this is also known as a critical hit. You can also critically fail a check. The rules for critical failure—sometimes called a fumble—are the same as those for a critical success, but in the other direction: if you fail a check by 10 or more, that's a critical failure.

Some actions and abilities have stronger effects on a critical success or failure. For example, a Strike deals double damage on a critical hit. If an effect doesn't list a critical success effect, the critical success effect is the same as the success effect, and the same goes for critical failures.

Fortune and Misfortune

Fortune and misfortune effects can alter how you roll your dice. These abilities might allow you to reroll a failed roll, force you to reroll a successful roll, allow you to roll twice and use the higher result, or force you to roll twice and use the lower result.

You can never have more than one fortune effect or misfortune effect come into play on a single roll. For instance, if an effect lets you roll twice and use the higher roll, you can't then use Halfling Luck (a fortune effect) to reroll if you fail. If multiple fortune effects would apply, you have to pick which to use. If two misfortune effects apply, the GM decides which is worse and applies it.

If both a fortune effect and a misfortune effect would apply to the same roll, the two cancel each other out, and you roll normally.

Natural 1 and Natural 20

Source Player Core pg. 401 2.0
If you rolled a 20 on the die (a “natural 20”), your result is one degree of success better than it would be by numbers alone. If you roll a 1 on the d20 (a “natural 1”), your result is one degree worse. This means that a natural 20 usually results in a critical success and natural 1 usually results in a critical failure. However, if you were going up against a very high DC, you might get only a success with a natural 20, or even a failure if 20 plus your total modifier is 10 or more below the DC. Likewise, if your modifier for a statistic is so high that adding it to a 1 from your d20 roll exceeds the DC by 10 or more, you can succeed even if you roll a natural 1!

Certain abilities can change the degree of success on a roll. When resolving such an ability, apply the adjustment from a natural 20 or natural 1 before anything else.

Attack Rolls

Source Player Core pg. 402 2.0
When you use a Strike action or make a spell attack, you attempt a check called an attack roll. Attack rolls take a variety of forms and are often highly variable based on the weapon you are using for the attack, but there are three main types: melee attack rolls, ranged attack rolls, and spell attack rolls. Spell attack rolls work a little bit differently, so they are explained separately on the next page.

Melee attack rolls use Strength as their attribute modifier by default. If you're using a weapon or attack with the finesse trait, then you can use your Dexterity modifier instead.

Melee attack roll result = d20 roll + Strength modifier (or optionally Dexterity modifier for a finesse weapon) + proficiency bonus + other bonuses + penalties

Ranged attack rolls use Dexterity as their attribute modifier.

Ranged attack roll result = d20 roll + Dexterity modifier + proficiency bonus + other bonuses + penalties

When attacking with a weapon, whether melee or ranged, you add your proficiency bonus for the weapon you're using. Your class determines your proficiency rank for various weapons. Sometimes, you'll have different proficiency ranks for different weapons or groups of weapons.

The bonuses you might apply to attack rolls can come from a variety of sources. Circumstance bonuses can come from the aid of an ally or a beneficial situation. Status bonuses are typically granted by spells and other magical aids. The item bonus to attack rolls comes from magic weapons—notably, a weapon's potency rune (GM Core, page 236).

Penalties to attack rolls come from situations and effects as well. Circumstance penalties come from risky tactics or detrimental circumstances, status penalties come from spells and magic working against you, and item penalties occur when you use a shoddy item (page 270). When making attack rolls, two main types of untyped penalties are likely to apply. The first is the multiple attack penalty, and the second is the range penalty. The first applies anytime you make more than one attack action during the course of your turn, and the other applies only with ranged or thrown weapons. Both are described below.

Multiple Attack Penalty

Source Player Core pg. 402 2.0
The more attacks you make beyond your first in a single turn, the less accurate you become, represented by the multiple attack penalty. The second time you use an attack action during your turn, you take a –5 penalty to your check. The third time you attack, and on any subsequent attacks, you take a –10 penalty to your check. Every check that has the attack trait counts toward your multiple attack penalty, including Strikes, spell attack rolls, certain skill actions like Shove, and many others.

Some weapons and abilities reduce multiple attack penalties, such as agile weapons, which reduce these penalties to –4 on the second attack or –8 on further attacks.

Multiple Attack Penalty

AttackMultiple Attack PenaltyAgile
FirstNoneNone
Second-5-4
Third and subsequent-10-8

Always calculate your multiple attack penalty based on the weapon you're using on that attack, not ones you used on previous attacks. For example, let's say you're wielding a longsword in one hand and a shortsword (which has the agile trait) in your other hand, and you make three Strikes with these weapons over the course of your turn. The first Strike you make during your turn has no penalty, no matter what weapon you are using. The second Strike will take either a –5 penalty if you use the longsword or a –4 penalty if you use the shortsword. Your third attack would be a –10 penalty with the longsword and a –8 penalty with the shortsword, no matter what weapon you used for your previous Strikes.

The multiple attack penalty applies only during your turn, so you don't have to keep track of it if you can perform a Reactive Strike or a similar reaction that lets you make a Strike on someone else's turn.

Range Penalty

Source Player Core pg. 403 2.0
Ranged and thrown weapons each have a listed range increment, and attacks with them grow less accurate against targets farther away (range and range increments are covered in depth on page 426). As long as your target is at or within the listed range increment, also called the first range increment, you take no penalty to the attack roll. If you're attacking beyond that range increment, you take a –2 penalty for each additional increment beyond the first. You can attempt to attack with a ranged weapon or thrown weapon up to six range increments away, but the farther away you are, the harder it is to hit your target.

For example, the range increment of a crossbow is 120 feet. If you are shooting at a target no farther away than that distance, you take no penalty due to range. If they're beyond 120 feet but no more than 240 feet away, you take a –2 penalty due to range. If they're beyond 240 feet but no more than 360 feet away, you take a –4 penalty due to range, and so on, until you reach the last range increment: beyond 600 feet but no more than 720 feet away, where you take a –10 penalty due to range.

Compare to AC

Source Player Core pg. 403 2.0
You compare your attack roll to Armor Class (AC), a special type of DC. Learn how to calculate it on page 404.

Spell Attack Rolls

Source Player Core pg. 403 2.0
If you cast spells, you might need to make a spell attack roll. These rolls are usually made when you cast a spell that targets a creature's AC.

The attribute modifier for a spell attack roll depends on how you gained the spell. If your class grants you spellcasting, use your key attribute modifier (such as Intelligence for a wizard). Innate spells use your Charisma modifier unless the ability that granted them states otherwise. Focus spells and other sources of spells specify which attribute modifier you use for spell attack modifiers in the ability that granted them. If you have spells from multiple sources or traditions, you might use different attribute modifiers for spell attack modifiers for these different sources of spells. For example, a dwarf cleric with the Stonewalker ancestry feat would use her Charisma modifier when casting one with stone from that feat, since it's a divine innate spell, but she would use her Wisdom modifier when casting heal and other spells using her cleric divine spellcasting.

If you have the ability to cast spells, you'll have a proficiency rank for your spell attack modifier, so you'll always add a proficiency bonus. Spell attack rolls can benefit from circumstance bonuses and status bonuses, though item bonuses to spell attack rolls are rare. Penalties affect spell attack rolls just like any other attack roll—including your multiple attack penalty.

Calculate a spell attack roll with the following formula.

Spell attack roll result = d20 roll + spellcasting attribute modifier + proficiency bonus + other bonuses + penalties

Writing Down Statistics

When creating your character and adventuring you'll record the total modifier for various important checks on your character sheet. Since many bonuses and penalties are due to the immediate circumstances, spells, and other temporary magical effects, you typically won't apply them to your notations.

For example, the number you write down for your attack modifier with your battle axe would likely be your Strength modifier + your proficiency bonus with martial weapons. Your spell attack modifier is typically just your spellcasting attribute modifier + your proficiency bonus, and your spell DC is usually the same number + 10.

Item bonuses and penalties are often more persistent, so you will often want to record them ahead of time. For instance, if you upgraded your battle axe with a +1 weapon potency rune, you'll want to add the +1 item bonus into your attack modifier with the battle axe, since you will include that bonus every time you attack with that weapon.

Spell DC

Source Player Core pg. 403 2.0
Many times, instead of requiring you to make a spell attack roll, the spells you cast will require those within the area or targeted by the spell to attempt a saving throw against your spell DC to determine how the spell affects them. Calculate it using the following formula.

Spell DC = 10 + spellcasting attribute modifier + proficiency bonus + other bonuses + penalties


Defenses

Source Player Core pg. 404 2.0
Multiple statistics help you defend against attacks, spells, hazards, and other dangers of adventuring: Armor Class and three saving throws.

Armor Class

Source Player Core pg. 404 2.0
Attack rolls are compared to a special Difficulty Class called Armor Class (AC), which measures how hard it is for your foes to hit you with Strikes, spell attack rolls, and other attacks. Just like for any other check and DC, the result of an attack roll must meet or exceed your AC to be successful, which allows your foe to deal damage to you. Armor Class is calculated using the following formula.

Armor Class = 10 + Dexterity modifier (up to your armor's Dex Cap) + proficiency bonus + armor's item bonus to AC + other bonuses + penalties

Use your proficiency bonus for the category (light, medium, or heavy) or the specific type of armor you're wearing. If you're not wearing armor, use your proficiency in unarmored defense.

Armor Class can benefit from bonuses with a variety of sources, much like attack rolls. Armor itself grants an item bonus, so other item bonuses usually won't apply to your AC, but magic armor can increase the item bonus granted by your armor.

Penalties to AC come from situations and effects in much the same way bonuses do. Circumstance penalties come from unfavorable situations, and status penalties come from effects that impede your abilities or from broken armor. You take an item penalty when you wear shoddy armor (page 270).

Saving Throws

Source Player Core pg. 404 2.0
There are three types of saving throws: Fortitude saves, Reflex saves, and Will saves. These are frequently called “saves”—it's the same thing. Saving throws measure your ability to shrug off harmful effects in the form of afflictions, damage, or conditions. You'll always add a proficiency bonus to each save. Your class might give a different proficiency to each save, but you'll be trained at minimum. Some circumstances and spells might give you circumstance or status bonuses to saves, and you might find resilient armor or other magic items that give an item bonus.

Fortitude saving throws allow you to reduce the effects of abilities and afflictions that can debilitate the body. They use your Constitution modifier and are calculated as shown in the formula below.

Fortitude save result = d20 roll + Constitution modifier + proficiency bonus + other bonuses + penalties

Reflex saving throws measure how well you can respond quickly to a situation and how gracefully you can avoid effects that have been thrown at you. They use your Dexterity modifier and are calculated as shown in the formula below.

Reflex save result = d20 roll + Dexterity modifier + proficiency bonus + other bonuses + penalties

Will saving throws measure how well you can resist attacks to your mind and spirit. They use your Wisdom modifier and are calculated as shown in the formula below.

Will save result = d20 roll + Wisdom modifier + proficiency bonus + other bonuses + penalties

Sometimes you'll need to know your DC for a given saving throw (such as a Grapple attempt requiring a roll against your Reflex DC). Like any other DC derived from a modifier, the DC for a saving throw is 10 + the total modifier for that saving throw.

Most of the time, when you attempt a saving throw, you don't have to use your actions or your reaction. You don't even need to be able to act to attempt saving throws. However, in some special cases you might have to take an action to attempt a save. For instance, you can try to recover from the sickened condition by spending an action to attempt a Fortitude save.

Basic Saving Throws

Source Player Core pg. 404 2.0
Sometimes you will be called on to attempt a basic saving throw (or “basic save”). This type of saving throw works just like any other saving throw—the “basic” part refers to the effects. For a basic save, you'll attempt the check and determine whether you critically succeed, succeed, fail, or critically fail like you would any other saving throw. Then one of the following outcomes applies based on your degree of success—no matter what caused the saving throw. Some spells or abilities add an additional effect on certain results but still use a basic saving throw for brevity.

Critical Success You take no damage from the effect.
Success You take half the listed damage from the effect.
Failure You take the full damage listed from the effect.
Critical Failure You take double the listed damage from the effect.

Perception

Source Player Core pg. 404 2.0
Perception measures your ability to be aware of your environment. Every creature has Perception, which works with and is limited by a creature's senses. (Details on senses and detecting things are on page 434). Whenever you need to attempt a check based on your awareness, you'll attempt a Perception check. Your Perception uses your Wisdom modifier, so you'll use the following formula when attempting a Perception check.

Perception check result = d20 roll + Wisdom modifier + proficiency bonus + other bonuses + penalties

Nearly all creatures are at least trained in Perception, so you will almost always add a proficiency bonus to your Perception modifier. You might add a circumstance bonus for advantageous situations or environments and typically get status bonuses from spells or other magical effects. Items can also grant you a bonus to Perception, typically in a certain situation. For instance, a fine spyglass grants a +1 item bonus to Perception when attempting to see something a long distance away. Circumstance penalties to Perception occur when an environment or situation (such as fog) hampers your senses, while status penalties typically come from conditions, spells, and magic effects that foil the senses. You'll rarely encounter item penalties or untyped penalties for Perception.

Many abilities are compared to your Perception DC to determine whether they succeed. As with any DC based on a modifier, your Perception DC is 10 + your total Perception modifier.
Item Bonsues for Common items
Ability/SkillItemBonusLevelCategoryConsumable?Note
PerceptionMagnifying Glass+13Adventuring GearNoPerception checks to notice minute details of documents, fabric, and the like
PerceptionMagnifying Scope+13ScopesNoVisual Perception checks to Seek creatures through the scope
PerceptionSpyglass (Fine)+14Adventuring GearNoPerception checks to notice details at a distance
PerceptionEye Slash (Greater)+14TattoosNoVisual Perception checks
PerceptionGoggles of Night+15Other Worn ItemsNoPerception checks involving sight
PerceptionDarkvision Scope+15ScopesNoPerception checks involving sight in areas of dim light visible through the scope (as well as in areas of darkness, if the scope has been activated).
PerceptionMirror Goggles (Lesser)+15Other Worn ItemsNoVisual Perception checks
PerceptionObsidian Goggles+15Other Worn ItemsNoPerception checks involving sight
PerceptionEye of the Unseen+18ProsthesesNoVisual Perception checks
PerceptionClarity Goggles (Lesser)+18Other Worn ItemsNoVisual Perception checks
PerceptionCodex of Unimpeded Sight (Greater)+112GrimoiresNoPerception checks to Seek
PerceptionEagle-Eye Elixir (Lesser)+11Alchemical ElixirsYesPerception checks that is greater when attempting to find secret doors and traps.
PerceptionSerene Mutagen (Lesser)+11Alchemical ElixirsYes—
PerceptionDrakeheart Mutagen (Lesser)+11Alchemical ElixirsYes—
DiplomacyDiplomat's Charcuterie+13Alchemical FoodYesDiplomacy checks to Make an Impression
PerceptionEyes of the Eagle+29Other Worn ItemsNoPerception checks that involve sight
PerceptionMagnifying Scope (Greater)+29ScopesNoVisual Perception checks to Seek creatures through the scope
PerceptionEye Slash (Major)+29TattoosNoVisual Perception checks
PerceptionJann's Prism+29Held ItemsNovisual Perception checks
PerceptionSun Sight+210TattoosNoVisual Perception checks
PerceptionGoggles of Night (Greater)+211Other Worn ItemsNoPerception checks involving sight
PerceptionMirror Goggles (Moderate)+211Other Worn ItemsNoVisual Perception checks
PerceptionObsidian Goggles (Greater)+211Other Worn ItemsNoPerception checks involving sight
PerceptionSpectacles of Inquiry+212Other Worn ItemsNo—
PerceptionScope of Truth+213ScopesNoPerception checks made to Seek in areas you can see through the scope
PerceptionClarity Goggles (Moderate)+213Other Worn ItemsNoVisual Perception checks
PerceptionEye of the Unseen (Greater)+214ProsthesesNoVisual Perception checks
PerceptionDarkvision Scope (Greater)+215ScopesNoPerception checks involving sight in areas of dim light visible through the scope (as well as in areas of darkness, if the scope has been activated).
PerceptionAmulet of the Third Eye+217Other Worn ItemsNo—
PerceptionSerene Mutagen (Moderate)+23Alchemical ElixirsYes—
PerceptionDrakeheart Mutagen (Moderate)+23Alchemical ElixirsYes—
PerceptionZerk+24DrugsYesPerception rolls for initiative
PerceptionEagle-Eye Elixir (Moderate)+25Alchemical ElixirsYesPerception checks that is greater when attempting to find secret doors and traps.
PerceptionMagnifying Scope (Major)+317ScopesNoVisual Perception checks to Seek creatures through the scope
PerceptionEye Slash (True)+317TattoosNoVisual Perception checks
PerceptionGoggles of Night (Major)+318Other Worn ItemsNoPerception checks involving sight
PerceptionMirror Goggles (Greater)+318Other Worn ItemsNoVisual Perception checks
PerceptionObsidian Goggles (Major)+318Other Worn ItemsNoPerception checks involving sight
PerceptionThird Eye+319Other Worn ItemsNo—
PerceptionClarity Goggles (Greater)+319Other Worn ItemsNoVisual Perception checks
PerceptionEagle-Eye Elixir (Greater)+310Alchemical ElixirsYesPerception checks that is greater when attempting to find secret doors and traps.
PerceptionSerene Mutagen (Greater)+311Alchemical ElixirsYes—
PerceptionDrakeheart Mutagen (Greater)+311Alchemical ElixirsYes—
PerceptionEagle-Eye Elixir (Major)+316Alchemical ElixirsYesPerception checks that is greater when attempting to find secret doors and traps.
PerceptionSerene Mutagen (Major)+417Alchemical ElixirsYes—
PerceptionDrakeheart Mutagen (Major)+417Alchemical ElixirsYes—
Item Bonsues for Uncommon/Rare/Unique items
Ability/SkillItemBonusLevelCategoryConsumable?Note
PerceptionHigh-Contrast Goggles+10Adventuring GearNo—
PerceptionVestige Lenses+13Alchemical OtherNoPerception checks to Seek any alchemical vapors
PerceptionSkinsaw Mask+13Other Worn ItemsNoPerception checks to Seek frightened creatures
PerceptionStalk Goggles (Greater)+13Other Worn ItemsNoPerception checks involving sight
PerceptionSkinsaw Mask+13Other Worn ItemsNoSeek frightened creatures
PerceptionSleuth's Pipe+13Relic SeedsNoPerception checks to Sense Motive
PerceptionCovenant Tea+13TeaNoTo Perception DC
PerceptionSeer's Flute+14CodaNowhile playing the flute
PerceptionRing of the Tiger +15Other Worn ItemsNoPerception checks made in outdoor wilderness areas
PerceptionStag's Helm+16Other Worn ItemsNo—
PerceptionGhost Scarf+17Held ItemsNoAll Perception checks and Perception DCs to resolve discovering a haunt or rolling initiative when a haunt triggers.
PerceptionSpiritsight Tea+17TeaNoPerception checks to Seek incorporeal creatures.
PerceptionUmbral Wings+18Other Worn ItemsNoChecks to Seek
PerceptionSeer's Flute (Greater)+18CodaNowhile playing the flute
PerceptionDiviner's Nose Chain+19Other Worn ItemsNoSeek or Sense Motive
PerceptionDrazmorg's Staff of All-Sight+110StavesNoVisual Perception checks
PerceptionSkeptic's Elixir (Lesser)+11Alchemical ElixirsYesPerception checks and Perception DCs to notice falsehoods, whether they're spoken lies or written deceit
PerceptionGrim Ring+25Other Worn ItemsNoSecret Perception checks against undead in the area that are hiding or disguised
PerceptionSpiritsight Ring+26Other Worn ItemsNoSeek to find hidden or undetected incorporeal creatures within 30 feet of you
PerceptionStalk Goggles (Major)+28Other Worn ItemsNoPerception checks involving sight
PerceptionStarless Scope+29Held ItemsNoPerception checks made to observe the skies
PerceptionAeon Stone (Cymophane Cabochon)+29Other Worn ItemsNo—
PerceptionRing of the Tiger (Greater)+210Other Worn ItemsNoPerception checks made in outdoor wilderness areas
PerceptionSpectral Opera Glasses+211Held ItemsNo—
PerceptionBring Me Near+212Held ItemsNoVisual Perception checks
PerformanceSeer's Flute (Major)+212CodaNowhile playing the flute
PerceptionExploration Lens (Searching)+214Held ItemsNoPerception checks to spot hidden doors and concealed hazards while Searching
PerceptionThe Big Sky+220The Deck of DestinyNoPerception checks made while flying outside during the day (+3 at 17th level)
PerceptionThe Trumpet+220The Deck of DestinyNoinitiative checks made with hearing-based Perception checks
PerceptionThe Owl+220The Deck of DestinyNoPerception checks made to Sense Motive (+3 at 17th level).
PerceptionThe Inquisitor+220The Deck of DestinyNoPerception checks to Sense Motive against creatures higher level than you (+3 at 17th level).
PerceptionThe Unicorn+220The Deck of DestinyNoPerception checks to Seek (+3 at 17th level).
PerceptionThe Winged Serpent+220The Deck of DestinyNosight-based Perception checks for initiative (+3 at 17th level).
PerceptionSkeptic's Elixir (Moderate)+26Alchemical ElixirsYesPerception checks and Perception DCs to notice falsehoods, whether they're spoken lies or written deceit
PerceptionOmmatophoric Mutagen+27Alchemical ElixirsYesvisual Perception checks
PerceptionPallesthetic Mutagen+29Alchemical ElixirsYesPerception checks using the granted senses
PerceptionEnergizing Pill+210Alchemical FoodYesItem bonus to initiative rolls with Perception.
PerceptionDragonfly Potion+212PotionsYesVisual Perception checks
PerceptionRobe of Eyes+317Other Worn ItemsNo—
PerceptionVoid Mirror+320ArtifactsNoPerception checks made while using the mirror
PerceptionSkeptic's Elixir (Greater)+311Alchemical ElixirsYesPerception checks and Perception DCs to notice falsehoods, whether they're spoken lies or written deceit

Perception for Initiative

Source Player Core pg. 405 2.0
Often, you’ll roll a Perception check to determine your order in initiative. When you do this, instead of comparing the result against a DC, the GM will put the results for everyone in the encounter in order. The creature with the highest result acts first, the creature with the second-highest result goes second, and so on. Sometimes you may be called on to roll a skill check for initiative instead, but you’ll compare results just as if you had rolled Perception. The full rules for initiative are found in the rules for encounter mode on page 435.

Skill Checks

Source Player Core pg. 405 2.0
Pathfinder has a variety of skills, from Athletics to Medicine to Occultism. Each grants you a set of related actions that rely on you rolling a skill check. Each skill has a key attribute modifier, based on the scope of the skill in question. For instance, Athletics deals with feats of physical prowess, like swimming and jumping, so its key attribute modifier is Strength. Medicine deals with the ability to diagnose and treat wounds and ailments, so its key attribute modifier is Wisdom. The key attribute modifier for each skill is listed on page 227 in Chapter 4: Skills. No matter which skill you're using, you calculate a check for it using the following formula.

Skill check result = d20 roll + the skill's key attribute modifier + proficiency bonus + other bonuses + penalties

You're unlikely to be trained in every skill. As normal, when using a skill in which you're untrained, your proficiency bonus is +0; otherwise, it equals your level plus 2 for trained, or higher once you become expert or better. The proficiency rank is specific to the skill you're using. Aid from another character or some other beneficial situation may grant you a circumstance bonus. A status bonus might come from a helpful spell or magical effect. Sometimes tools related to the skill grant you an item bonus to your skill checks. Conversely, unfavorable situations might give you a circumstance penalty to your skill check, while harmful spells, magic, or conditions might also impose a status penalty. Using shoddy or makeshift tools might cause you to take an item penalty. Sometimes a skill action can be an attack, and in these cases, the skill check might take a multiple attack penalty, as described on page 234.

When an ability calls for you to use the DC for a specific skill, you can calculate it by adding 10 + your total modifier for that skill.

Flat Checks

When the chance something will happen or fail to happen is based purely on chance, you'll attempt a flat check. A flat check never includes any modifiers, bonuses, or penalties—you just roll a d20 and compare the result on the die to the DC. Only abilities that specifically apply to flat checks can change the checks' DCs; most such effects affect only certain types of flat checks.

If more than one flat check would ever cause or prevent the same thing, just roll once and use the highest DC. In the rare circumstance that a flat check has a DC of 1 or lower, skip rolling; you automatically succeed. Conversely, if one ever has a DC of 21 or higher, you automatically fail.

Secret Checks

Sometimes you as the player shouldn't know the exact result and effect of a check. In these situations, the rules (or the GM) will call for a secret check. The secret trait appears on anything that uses secret checks. This type of check uses the same formulas you normally would use for that check, but is rolled by the GM, who doesn't reveal the result. Instead, the GM simply describes the information or effects determined by the check's result. If you don't know a secret check is happening (for instance, if the GM rolls a secret Fortitude save against a poison that you failed to notice), you can't use any fortune or misfortune abilities (see the sidebar on page 401) on that check, but if a fortune or misfortune effect would apply automatically, the GM applies it to the secret check. If you know that the GM is attempting a secret check—as often happens with Recall Knowledge or Seek—you can usually activate fortune or misfortune abilities for that check. Just tell the GM, and they'll apply the ability to the check.

The GM can choose to make any check secret, even if it's not usually rolled secretly. Conversely, the GM can let you roll any check yourself, even if that check would usually be secret. Some groups find it simpler to have players roll all secret checks and just try to avoid acting on any outof-character knowledge, while others enjoy the mystery.