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Chapter 5: Skills

Skill Checks

Source Starfinder Core Rulebook pg. 132
No matter how skilled you become, when using skills, success is rarely certain. To determine whether you succeed when using a skill, you attempt a skill check: roll 1d20 and add your total skill bonus to the roll. Your total skill bonus includes the following.
  • Skill Ranks: Each skill rank you’ve invested in the skill increases your total skill bonus by 1.
  • Trained Class Skill Bonus: If the skill is a trained class skill for you, you gain a +3 bonus.
  • Associated Ability Score Modifier: Each skill has an associated ability score modifier listed in its entry; add this modifier to your total skill bonus.
  • Other Modifiers: Sometimes your race, your feats, items you are using, spells affecting you, or other mitigating circumstances confer additional bonuses or penalties. For instance, any skill with “armor check penalty” listed in its heading is harder to use effectively while wearing bulky armor, and you apply an armor check penalty (see page 196) to all skill checks of that type while wearing such armor.
The total of 1d20 + your total skill bonus is referred to as the result of your skill check. If the result of your skill check equals or exceeds the difficulty class (also called the DC) of the task you are attempting, you succeed. If the total is less than the DC, you fail. Sometimes a task features varying degrees of success or failure depending on how much your result is above or below the required DC. The GM is responsible for determining the DCs of skill checks (see Skill DCs on page 392 for more details).

Often, using a skill requires taking an action, or it is taken as part of some other action. The action depends on the skill and the specific task listed in that skill. Each skill description details a number of common tasks for which that skill is used. Your GM will also prompt you to roll nonstandard skill checks when the circumstances of the game demand it.

Sometimes you attempt a skill check not to accomplish a task, but to thwart someone else’s task or action. This is called an opposed skill check. With an opposed skill check, one creature attempts a skill check to try accomplish some action or task, while another creature attempts its own skill check to determine the DC the first creature must meet or exceed to accomplish its goal. Typically, attempting an opposed skill check to determine the DC requires no action, but it often requires you to be conscious or have the ability to take certain types of actions when you do so.

On occasion, it’s impossible for you to attempt a skill check. Sometimes the situation prevents you from rolling a skill check, and other times the skill in question requires special training in order to attempt. Skills that require special training are called trained-only skills and are marked as such in their headings. Unless otherwise noted in the skill’s description, you can’t attempt an untrained skill check to accomplish a task using a trained-only skill; you must have at least 1 rank in that skill to attempt a check.

The table that begins the following page summarizes the differences between trained and untrained skills.

Skill Check TypeSkill Check Result
Trained class skill1d20 + skill ranks + 3 + ability score modifier + other modifiers*
Trained skill1d20 + skill ranks + ability score modifier + other modifiers*
Untrained skill1d20 + ability score modifier + other modifiers*
* Armor check penalties apply to most Strength- and Dexterity-based skill checks.

Take 10

Most of the time, you attempt skill checks while under pressure or during times of great stress. Other times, the situation is more favorable, making success more certain.

When you are not in immediate danger or distracted, the GM might allow you to take 10 on a skill check. When you take 10, you don’t roll a d20, but rather assume that you rolled a 10 on that die, then add the relevant skill modifiers. For many routine tasks, or for tasks you are particularly skilled at, taking 10 ensures success. If you still fail when taking 10, you might require more time and energy to succeed at that task (see Take 20 below).

Unless you have an ability that states otherwise, you cannot take 10 during a combat encounter. Also, you can’t take 10 when the GM rules that a situation is too hectic or that you are distracted, and taking 10 is almost never an option for a check that requires some sort of crucial effect as a key part of the adventure’s story.

Take 20

When you have plenty of time to devote to a skill’s task and that task has no adverse effect upon failure, the GM might rule that you can take 20 on that skill check. This is similar to taking 10, but instead of assuming your roll was a 10, you assume it’s a 20.

Taking 20 means you are making multiple attempts at the task until you get it right. It also assumes that you are failing many times before you succeed. Taking 20 typically takes 20 times as long as attempting a single check would take (usually 2 minutes for a skill that takes a standard action to perform).

Aid Another

The GM might rule that you can help someone succeed at a skill check by performing the same action and attempting a skill check as part of a cooperative effort. To do so, you must attempt your skill check before the creature you want to help, and if you succeed at a DC 10 check, that creature gains a +2 bonus to his check, as long as he attempts the check before the end of his next turn. At the GM’s discretion, only a limited number of creatures might be able to aid another. You cannot take 10 or take 20 on an aid another check, but you can use aid another to help a creature who is taking 10 or 20 on a check.