Skills

Making Skill Checks: Unless stated otherwise, skill checks are free actions. When a character attempts an action that requires a skill check, the player rolls a d20 and adds the character's skill modifier (their ranks in the skill + the relevant ability modifier + any other modifiers). The GM compares the result against the difficulty class (DC) of the skill check. If the result is equal to or higher than the DC, the character passes the skill check; otherwise, they fail. Some checks use degrees of success; if you pass, this is equal to 1 plus 1 for every 10 you pass by.

Skill DC: When one character attempts a check against another, the check DC is sometimes a skill DC, such as "perception DC". The check DC is equal to 10 + the other character's skill modifier.

Skill Points: Whenever a character takes a long rest, their total skill points are set to (1 + level/2) x intelligence score - skill ranks, minimum 0. Intelligence score modifiers only apply if they last for the entire long rest. Simply put, a level 0 character gains skill points equal to their intelligence score, and gains half as much each time they level up, with odd scores rounding up on even levels.

Spending Skill Points: When a character gains skill points, they may spend any of them on skill ranks. Each point spent grants them 1 rank in a chosen skill, to a maximum rank of 3 + level. If a character chooses not to spend all their skill points, they may spend one each time they make a skill check, but only on that skill; they may spend this point after they roll but before the result of the check happens.

Subskills: Some skills are very similar to others, mechanically. These skills are grouped together under one skill, such as Craft, Knowledge, or Profession. These "subskills" function like normal skills in nearly every way, except they share ways to use them listed under the one skill. Whenever you have to choose a skill, such as when spending skill points or applying a bonus to a chosen skill, you can't choose a skill with subskills, only the subskills themselves.

Skill Uses: Each skill has different uses, which may be affected individually. Some skill uses roll other ones, such as Reduce Falling Damage rolling a Jump check.

Taking Damage: Whenever a character takes damage, it gets a penalty to all skill checks until the end of its next turn. This penalty equals the damage it took after resistances, minus its level. These penalties stack.