3e SRD:Using Skills
Using Skills
When the character uses a skill, the character makes a skill check to see how well the character does. The higher the result on the character's skill check, the better the character does. Based on the circumstances, the character's result must match or beat a particular number to use the skill successfully. The harder the task, the higher the number the character needs to roll.
Skill Checks
To make a skill check, roll 1d20 and add the character's skill modifier for that skill. The skill modifier incorporates the character's rank with that skill, the character's ability modifier for that skill's key ability, and any other miscellaneous modifiers the character has, including racial bonuses and any armor check penalty. The higher the result, the better. A natural 20 is not an automatic success, and a natural 1 is not an automatic failure.
Difficulty Class
Some checks are made against a Difficulty Class (DC). The DC is a number that the character must score as a result on the character's skill check to succeed.
Opposed Checks
Some skill checks are opposed checks. They are made against a randomized number, which is usually another character's skill check result. Whoever gets the higher result wins the contest.
For ties on opposed checks, the character with the higher key ability score wins.
If these scores are the same, flip a coin.
Trying Again
In general, the character can try a skill check again if the character fails, and can keep trying indefinitely. Some skills, however, have consequences of failure that must be taken into account. Some 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.
If a skill carries no penalties for failure, the character can take 20 and assume that the character goes at it long enough to succeed eventually.
Untrained Skill Checks
Generally, if the character attempts to use a skill the character doesn't possess, the character makes a skill check as normal. The character's skill modifier doesn't have the character's skill rank added in because the character doesn't have any ranks in the skill. The character does get other modifiers added into the skill modifier, though, such as the ability modifier for the skill's key ability.
Many skills can only be used if the character is trained in the skill. Skills that cannot be used untrained are marked with a "No" in the "Untrained" column on Table: Skills.
Favorable and Unfavorable Conditions
Some situations may make a skill easier or harder to use, resulting in a bonus or penalty added into the skill modifier for the skill check or a change to the DC of the skill check.
The DM can alter the odds of success in four ways to take into account exceptional circumstances:
1. Give the skill user a +2 circumstance bonus to represent circumstances that improve performance.
2. Give the skill user a –2 circumstance penalty to represent conditions that hamper performance.
3. Reduce the DC by 2 to represent circumstances that make the task easier.
4. Increase the DC by 2 to represent circumstances that make the task harder.
A bonus to the character's skill modifier and a reduction in the check's DC have the same result: they create a better chance that the character will succeed. 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-equivalent 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. The distance the character jumps when making a Jump check, for example, is part of the character's movement. Some skills take more than a round to use, and the skill descriptions often specify how long these skills take to use.
Practically Impossible Tasks
In general, to do something that's practically impossible requires that the character have at least rank 10 in the skill and entails a penalty of –20 on the character's roll or +20 on the DC (which amounts to about the same thing).
Practically impossible tasks are hard to delineate ahead of time. They're the accomplishments that represent incredible, almost logic-defying skill and luck.
The DM decides what is actually impossible and what is merely practically impossible.
Extraordinary Success
If the character has at least rank 10 in a skill and beats the DC by 20 or more on a normal skill check, the character has completed the task impossibly well.
Taking 10
When the character is not in a rush and is not being threatened or distracted, the character may choose to take 10. Instead of rolling 1d20 for the skill check, calculate the character's result as if the character had rolled a 10.
Taking 20
When the character has 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), and when the skill being attempted carries no penalties for failure, the character can take 20.
Instead of rolling 1d20 for the skill check, calculate the character's result as if the character had rolled a 20. Taking 20 means the character is trying until the character gets it right. Taking 20 takes about twenty times as long as making a single check would take.
Combining Skill Checks
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 on her own.
Aid Another
Sometimes the individual PCs are essentially reacting to the same situation, but they can work together and help each other out. In this case, one character is considered the leader of the effort and makes a skill check while each helper makes a skill check against DC 10. (the character can't take 10 on this check.) For each helper who succeeds, the leader gets a +2 circumstance bonus (as per the rule for favorable conditions). In many cases, a character's help won't be beneficial, or only a limited number of characters can help at once. The DM limits cooperation as she sees fit for the given conditions.
Skill Synergy
It's also possible for a character to have two skills that work well together. In general, having 5 or more ranks in one skill gives the character a +2 synergy bonus on skill checks with its synergistic skills, as noted in the skill description.
Ability Checks
Sometimes the character tries to do something to which no specific skill really applies. In these cases, the character makes an ability check. An ability check is the roll of 1d20 plus the appropriate ability modifier. Essentially, the character is making an untrained skill check. The DM assigns a Difficulty Class.
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