Acquiring Skills
Skills Points and Skill Ranks
Each level, your character gains a number of skill points dependent upon your class plus your Intelligence modifier. You may spend these points to purchase ranks in a skill. Each rank represents a measure of training in that skill and is equivalent to a +1 bonus on all checks with that skill.
You can never have more ranks in a skill than your total number of Hit Dice.
Training Class Skills and Cross-Class Skills
Each class has a number of favored skills, called class skills. It is easier for your character to become more proficient in these skills, as they represent part of his professional training and constant practice. Cross-class skills are any skills which are not a class skill for your character’s current class.
When you spend skill points on a class skill, you gain 1 skill rank for each skill point spent.
When you spend skill points on a cross-class skill, you gain ½ rank per skill point. You may purchase half ranks in skills, but half ranks give no bonus to the check. However, any skill with at least half a rank counts as trained (see Untrained Skill Checks).
If you have levels in more than one class, only the class skills of the class level you are gaining count as class skills for spending skill points.
Skill Checks
When your character uses a skill, it isn’t a guaranteed success. To determine success or failure, you must make a skill check.
To make a skill check, roll:
1d20 + skill modifier (Skill modifier = skill rank + ability modifier + any 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. 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.
Opposed Checks
Some skill checks are opposed by the target’s skill. When making an opposed skill check, the attempt is successful if your check result exceeds 10 + the target’s bonus on that skill, as if the target decided to Take 10 on their check (see Checks Without Rolls below).
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. Many skills can be used even if the character has no ranks in them; doing this is called making an untrained skill check.
Untrained Skill Checks
Any skill may be used without training, but a character with zero ranks in a skill usually cannot succeed on any task with a DC higher than 10.
Ability Modifier
The ability modifier used in a skill check is the modifier for 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.
Armor Penalty
Certain types of armor impose a penalty to certain skill checks. Affected skills are noted in the skill’s description. (See Armor Check Penalty.)
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 for failure that must be taken into account. For most skills, when a character has succeeded once at a given task, additional successes are meaningless.
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. Taking 10 is especially useful in situations where a particularly high roll wouldn’t help.
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 roll 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 repeatedly 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 you could complete the task.
Ability Checks, Concentration 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.