Source Player Core pg. 183

While your character's attributes represent their raw talent and potential, skills represent their training and experience at performing certain tasks. Each skill is keyed to one of your character's attributes and used for an array of related actions. Your character's expertise in a skill comes from several sources, including their background and class. In this chapter, you'll learn about new skill options in Starfall, with new skills and updated uses for existing skills.

Skills

A character's acumen in skills can come from all sorts of training, from piloting starships to researching a topic on an infosphere to rehearsing a performing art. When you create your character and as they advance in level, you have flexibility as to which skills they become better at and when. Some classes benefit more from improving certain skills—such as the envoy's focus on their leadership skill—but for most classes, you can choose whichever skills make the most sense for your character's theme and backstory at 1st level, then use their adventure and downtime experiences to inform how their skills should improve as your character levels up.

A character gains training in certain skills at 1st level: typically two from their background, a small number of predetermined skills from their class, and several skills of your choice granted by their class. This training increases your proficiency ranks for those skills that are trained, rather than untrained, and allows you to use more of the skills' actions. Sometimes, you may become trained in the same skill from multiple sources, such as when your background grants training in Athletics and you take the Solarian class, which also grants training in Athletics. Each time after the first that you'd become trained in a given skill, you instead allocate the trained proficiency to any other skill of your choice—though if the skill is a Lore skill, the new skill must also be a Lore skill.

Improving Skills

As your character advances in level, there are two main ways their skills improve: skill increases and skill feats. Your class lists the levels at which you gain each of these improvements.

Skill Increases

Skill increases improve your proficiency in skills of your choice. You can use these increases to become trained in new skills or increase your proficiency rank in skills you're trained in (from trained to expert at any level, expert to master at 7th level or higher, and master to legendary at 15th level or higher). Unlike when you first become trained at a skill, if two different abilities would make you an expert, master, or legendary in a skill, you don't get to choose a second skill to become expert in—the redundant benefit simply has no effect.

Skill Feats

Skill feats are a type of general feat that often grant you a new way to use a skill or make you better at using a skill in a particular way. Skill feats always have the skill trait. 

Key Attribute

Each skill is tied to a key attribute. You add your modifier for this attribute to checks and DCs when using that skill. For example, skulking about the shadowy corridors of a derelict starship with Stealth uses your Dexterity modifier, navigating the fickle personalities and treacherous power plays of interstellar politics with Society uses your Intelligence modifier, and so on. The key attribute for each skill is listed on the Skills, Key Attributes, and Actions and also appears in parentheses following the skill's name in the descriptions on the following pages. If the GM deems it appropriate for a certain situation, however, they might have you use a different attribute modifier for a skill check or when determining your skill DC.

Skill Actions

The actions you can perform with a given skill are sorted into those you can use untrained and those that require you to be trained in the skill, as shown on the Skills, Key Attributes, and Actions table. The untrained and trained actions of each skill appear in separate sections within the skill's description.

Anyone can use a skill's untrained actions, but you can use trained actions only if you have a proficiency rank of trained or better in that skill. A circumstance, condition, or effect might bar you from a skill action regardless of your proficiency rank, and sometimes using a skill in a specific situation might require you to have a higher proficiency rank than what is listed on the table. For instance, even though a soldier untrained in Occultism could identify an extraplanar or eldritch being with a lucky roll using Occultism to Recall Knowledge, the GM might decide that Recalling Knowledge to determine the spells used to summon and control such a creature is beyond the scope of the soldier's anecdotal knowledge. The GM decides whether a task requires a particular proficiency rank.

Skills, Attributes, and Actions

Skill Checks and DCs

When you're actively using a skill, often by performing one of its actions, you might attempt a skill check: rolling a d20 and adding your skill modifier. To determine this modifier, add your attribute modifier for the skill's key attribute, your proficiency bonus for the skill, and any other bonuses and penalties.

Skill modifier = skill's key attribute modifier + proficiency bonus + other bonuses + penalties

When noting the modifier on your character sheet, you should write down only the numbers that always apply—typically just your attribute modifier and proficiency bonus at 1st level. At higher levels, you may wear or use items to improve your skills with item bonuses pretty much all the time; you should include those in your calculation, too.

The GM sets the DC of a skill check, using the guidelines in Starfinder GM Core. The DCs you're most likely to encounter frequently are the five simple skill DCs below, which are presented here to give you a sense of what number you'll need to roll to succeed at most tasks.

When someone or something tests your skill, they attempt a check against your skill DC, which is equal to 10 plus your skill modifier. A skill DC works like any other DC to determine the effect of an opposing creature's skill action.

Armor and Skills

Some armor imposes a penalty on specific skill checks and DCs. If a creature is wearing armor that imparts a skill penalty, that penalty is applied to the creature's Strength and Dexterity-based skill checks and skill DCs, unless the action has the attack trait. Check penalties from armor are detailed in the Armor section.

Exploration and Downtime Activities

Some skill activities have the 'exploration' or 'downtime' trait. Exploration activities usually take a minute or more, while downtime activities may take a day or more. They usually can't be used during an encounter, though the GM might bend this restriction. If you have the time to use one of these activities, ask your GM.