Skills:

Skill Points and Class skills:

Whenever you gain a level in a class, you gain more skill points. The number of skill points is listed under the classes table. However, you get additional skill points each level equal to your Intelligence score. If your Intelligence score permanently increases, you earn extra skill points as if you had always had that Intelligence score.

If you buy a class skill, your character gets 1 rank (equal to a +1 bonus on checks with that skill) for each skill point. If you buy other skills (cross-class skills), you get ½ rank per skill point.

If a skill is a class skill for any of your classes, it is a class skill for all of your classes. If you purchase ranks in a cross-class skill and that skill later becomes a class skill for you, those previously purchased ranks are doubled (as if they had always been a class skill).

Your maximum rank in a class skill is your character level.

Your maximum rank in a cross-class skill is one-half of this number (do not round up or down).

Skill Powers:

Each skill has a special Power connected to it; knowledge of this Power allows a character to use the skill in a new way or improves the skill's existing uses. Some characters (such as Experts) gain Skill Powers for free. However, any character can buy a Skill Power. If you have at least 3 ranks in a skill, you may pay 2 Skill Points to learn that skill's Skill Power.

Some skills have more than one Power. Each must be gained separately.

Skill Checks:

To make a skill check, roll: 1d20 + skill modifier

(Skill modifier = skill rank + ability score + miscellaneous modifiers)

This roll works just like an attack roll or a saving throw— the higher the roll, the better. Either you’re trying to match or exceed a certain Difficulty Class (DC), or you’re trying to beat another character’s check result.

Skill Ranks:
A character’s number of ranks in a skill is based on how many skill points a character has invested in a skill. Skills can be used even if the character has no ranks in them; doing this is called making an untrained skill check.

Ability Score:
The ability score used in a skill check is the skill’s key ability (the ability associated with the skill’s use). The key ability of each skill is noted in its description.

Miscellaneous Modifiers:
Miscellaneous modifiers include racial bonuses, armor check penalties, and bonuses provided by feats, among others.

Using Skills:

When your character uses a skill, you make a skill check to see how well he or she does. The higher the result of the skill check, the better. Based on the circumstances, your result must match or beat a particular number (a DC or the result of an opposed skill check) for the check to be successful. The harder the task, the higher the number you need to roll.

Circumstances can affect your check. A character who is free to work without distractions can make a careful attempt and avoid simple mistakes. A character who has lots of time can try over and over again, thereby assuring the best outcome. If others help, the character may succeed where otherwise he or she would fail.

Skill Checks:

A skill check takes into account a character’s training (skill rank), natural talent (ability score), and luck (the die roll). It may also take into account his or her race’s knack for doing certain things (racial bonus) or what armor he or she is wearing (armor penalty), or a certain feat the character possesses, among other things.

To make a skill check, roll 1d20 and add your character’s skill modifier for that skill. The skill modifier incorporates the character’s ranks in that skill and that skill’s key ability, plus any other miscellaneous modifiers that may apply, including racial bonuses and armor check penalties. The higher the result, the better. Unlike with attack rolls and saving throws, a natural roll of 20 on the d20 is not an automatic success, and a natural roll of 1 is not an automatic failure.

Difficulty Class:

Some checks are made against a Difficulty Class (DC). The DC is a number (set using the skill rules as a guideline) that you must score as a result on your skill check in order to succeed.

Difficulty Class scale:
Very easy (0)
Easy (5)
Average (10)
Tough (15)
Challenging (20)
Formidable (25)
Heroic (30)
Nearly impossible (40)

Opposed Checks:

An opposed check is a check whose success or failure is determined by comparing the check result to another character’s check result. In an opposed check, the higher result succeeds, while the lower result fails. In case of a tie, the higher skill modifier wins. If these scores are the same, roll again to break the tie.

Trying Again:

In general, you can try a skill check again if you fail, and you can keep trying indefinitely. Some skills, however, have consequences of failure that must be taken into account. A few skills are virtually useless once a check has failed on an attempt to accomplish a particular task. For most skills, when a character has succeeded once at a given task, additional successes are meaningless.

Untrained Skill Checks:

Generally, if your character attempts to use a skill he or she does not possess, you make a skill check as normal. The skill modifier doesn’t have a skill rank added in because the character has no ranks in the skill. Any other applicable modifiers, such as the modifier for the skill’s key ability, are applied to the check.

Some skills can be used only by someone who is trained in them.

Favorable and Unfavorable Conditions:

Some situations may make a skill easier or harder to use, resulting in a bonus or penalty to the skill modifier for a skill check or a change to the DC of the skill check.

The chance of success can be altered in four ways to take into account exceptional circumstances.

-Give the skill user a +2 circumstance bonus to represent conditions that improve performance, such as having the perfect tool for the job, getting help from another character (see Combining Skill Attempts), or possessing unusually accurate information.
-Give the skill user a -2 circumstance penalty to represent conditions that hamper performance, such as being forced to use improvised tools or having misleading information.
-Reduce the DC by 2 to represent circumstances that make the task easier, such as having a friendly audience or doing work that can be subpar.
-Increase the DC by 2 to represent circumstances that make the task harder, such as having an uncooperative audience or doing work that must be flawless.

Conditions that affect your character’s ability to perform the skill change the skill modifier. Conditions that modify how well the character has to perform the skill to succeed change the DC. A bonus to the skill modifier and a reduction in the check’s DC have the same result: They create a better chance of success. But they represent different circumstances, and sometimes that difference is important.

Time And Skill Checks:

Using a skill might take a round, take no time, or take several rounds or even longer. Most skill uses are standard actions, move actions, or full-round actions. Types of actions define how long activities take to perform within the framework of a combat round (6 seconds) and how movement is treated with respect to the activity. Some skill checks are instant and represent reactions to an event, or are included as part of an action.

These skill checks are not actions. Other skill checks represent part of movement.

Checks Without Rolls:

A skill check represents an attempt to accomplish some goal, usually while under some sort of time pressure or distraction. Sometimes, though, a character can use a skill under more favorable conditions and eliminate the luck factor.

Taking 10:
When your character is not being threatened or distracted, you may choose to take 10. Instead of rolling 1d20 for the skill check, calculate your result as if you had rolled a 10. For many routine tasks, taking 10 makes them automatically successful. Distractions or threats (such as combat) make it impossible for a character to take 10. In most cases, taking 10 is purely a safety measure; you know (or expect) that an average roll will succeed but fear that a poor roll might fail, so you elect to settle for the average roll (a 10). Taking 10 is especially useful in situations where a particularly high roll wouldn’t help.

Taking 20:
When you have plenty of time (generally 2 minutes for a skill that can normally be checked in 1 round, one full-round action, or one standard action), you are faced with no threats or distractions, and the skill being attempted carries no penalties for failure, you can take 20. In other words, eventually you will get a 20 on 1d20 if you roll enough times. Instead of rolling 1d20 for the skill check, just calculate your result as if you had rolled a 20.

Taking 20 means you are trying until you get it right, and it assumes that you fail many times before succeeding. Taking 20 takes twenty times as long as making a single check would take.

Since taking 20 assumes that the character will fail many times before succeeding, if you did attempt to take 20 on a skill that carries penalties for failure, your character would automatically incur those penalties before he or she could complete the task.

Ability Checks and Caster Level Checks:
The normal take 10 and take 20 rules apply for ability checks. Neither rule applies to caster level checks.

Combining Skill Attempts:

When more than one character tries the same skill at the same time and for the same purpose, their efforts may overlap.

Individual Events:
Often, several characters attempt some action and each succeeds or fails independently. The result of one character’s Parkour check does not influence the results of other characters Parkour check.

Aid Another:
You can help another character achieve success on his or her skill check by making the same kind of skill check in a cooperative effort. If you roll a 10 or higher on your check, the character you are helping gets a +2 bonus to his or her check, as per the rule for favorable conditions. (You can’t take 10 on a skill check to aid another.) In many cases, a character’s help won’t be beneficial, or only a limited number of characters can help at once.

In cases where the skill restricts who can achieve certain results you can’t aid another to grant a bonus to a task that your character couldn’t achieve alone.

Ability Checks:

Sometimes a character tries to do something to which no specific skill really applies. In these cases, you make an ability check. An ability check is a roll of 1d20 plus the appropriate ability score. Essentially, you’re making an untrained skill check.

In some cases, an action is a straight test of one’s ability with no luck involved. Just as you wouldn’t make a height check to see who is taller, you don’t make a Strength check to see who is stronger.