Skills represent some of the most basic and yet most fundamental abilities your character possesses. As your character advances in level, he can gain new skills and improve his existing skills dramatically.
Each level, your character gains a number of skill ranks dependent upon your class plus your Intelligence modifier. Investing a rank in a skill represents a measure of training in that skill. You can never have more ranks in a skill than your total number of Levels.
In addition, each class has a number of favoured skills, called class skills, selected when you first take a level in the class. It is easier for your character to become more proficient in these skills, as they represent part of his professional training and constant practice. You gain a +3 bonus on all class skills that you put ranks into. This +3 bonus counts as ranks in the skill for determining whether you meet the prerequisites of feats, and so on.
The number of skill ranks you gain when taking a level in one of the base classes is shown in each class description. Humans gain 1 additional skill rank per class level. If you select a level in a new class that grants more class skills than you previously had, you may select additional class skills up to that amount, and you gain a +3 bonus on these skills if you have ranks in them.
When your character uses a skill, he isn't guaranteed success. In order to determine success, whenever you attempt to use a skill, you must make a skill check. Each skill rank grants a +1 bonus on checks made using that skill. When you make a skill check, you roll 1d20 and then add your ranks and the appropriate ability score modifier to the result of this check. If the skill you're using is a class skill (and you have invested ranks into that skill), you gain a +3 bonus on the check. If you are not trained in the skill (and if the skill may be used untrained), you may still attempt the skill, but you use only the bonus (or penalty) provided by the associated ability score modifier to modify the check. Skills can be further modified by a wide variety of sources—by your race, by a class ability, by equipment, by spell effects or magic items, and so on. See Table: Skill Check Bonuses for a summary of skill check bonuses.
|Table: Skill Check Bonuses|
|Skill||Skill Check is Equal To*|
|Untrained||1d20 + ability modifier + racial modifier|
|Trained||1d20 + skill ranks + ability modifier + racial modifier|
|Trained Class Skill||1d20 + skill ranks + ability modifier + racial modifier + 3|
* Armour check penalty applies to all Strength- and Dexterity-based skill checks.
If the result of your skill check is equal to or greater than the difficulty class (or DC) of the task you are attempting to accomplish, you succeed. If it is less than the DC, you fail. Some tasks have varying levels of success and failure depending on how much your check is above or below the required DC. Some skill checks are opposed by the target's skill check. When making an opposed skill check, the attempt is successful if your check result exceeds the result of the target.
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 favourable conditions, increasing the odds of success.
Taking 10: When your character is not in immediate danger 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. The Mastery class ability allows you to take 10 on your selected skill, even when you would not normally be allowed to.
Taking 20: When you have plenty of time, 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, if you a d20 roll enough times, eventually you will get a 20. 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 20 times as long as making a single check would take (usually 2 minutes for a skill that takes 1 round or less to perform). Since taking 20 assumes that your character will fail many times before succeeding, your character would automatically incur any penalties for failure before he or she could complete the task (hence why it is generally not allowed with skills that carry such penalties). Common “take 20” skills include Disable Device (when used to open locks), Escape Artist, and Perception (when attempting to find traps).
Ability Checks and Caster Level Checks: The normal take 10 and take 20 rules apply for ability checks. Neither rule applies to concentration checks or caster level checks.
You can help someone achieve success on a 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're helping gets a +2 bonus on his or her check. (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, such as trying to open a lock using Disable Device, you can't aid another to grant a bonus to a task that your character couldn't achieve alone. The GM might impose further restrictions to aiding another on a case-by-case basis as well.
When circumstances allow you to aid another in this manner, then if your skill result is better than the character you're assisting (even with the +2 bonus you grant), then you may use your result in place of theirs. Be sure to role-play elbowing your ally out of the way to take over the task!
Some skill are related (list below). If you are competent at one, you may gain benefits to another. We call this a skill synergy. Skills that are related in this way are said to be synergised.
In the game, you can try to determine if your skill in one area helps you in another, on a case by case basis. Each time you need to make a skill check on a synergised skill, you may try, as a free action, to gain a bonus by making a synergy skill check. Roll a skill check on the related skill, with a DC of 15. If you succeed, you get a +2 bonus to the next synergised skill check. You cannot re-try a synergy check for the same skill check.
Example: You want to bluff an ogre that you're the new mercenaries hired to guard the dungeon. You can make a diplomacy check (a synergised skill with bluff) to try to gain a bonus to the bluff check. If your diplomacy check beats DC 15, then you gain a +2 synergy bonus to the next bluff check against the ogre.