A player should determine his or her adventurer's skill check modifier for each skill and record it on the character sheet.
A monster's skill check modifiers are listed in its stat block. If a skill check modifier is absent in a monster's stat block, then the monster uses its ability modifier related to that skill's key ability.
A creature's skill check modifier for a skill always includes the following.
- One-half the creature's level
- The creature's ability modifier for the skill's key ability (see below)
Any of these other factors might also apply to a skill check modifier.
- A +5 bonus if the creature has training in the skill (see below)
- An armor check penalty if the adventurer is wearing certain kinds of armor and the skill's key ability is Strength, Dexterity, or Constitution
- Any racial or feat bonuses
- Any item bonus from a magic item
- Any other bonuses or penalties that might apply
Skill Training
Having training in a skill means that a creature has some combination of formal instruction, practical experience, and natural aptitude using that skill. Skills a creature has training in are often called trained skills.
When a creature has training in a skill, it gains a +5 bonus to checks involving that skill. A creature can't gain training in a given skill more than once.
For adventurers, class descriptions specify how many skills a member of that class has training in and what skills a player may choose from at 1st level. For example, a player creating a 1st-level fighter (slayer) picks three skills from the slayer's list of class skills. Some feats, such as Skill Training, give an adventurer training in a skill even if it's not on the character's class skills list.
If a monster has any trained skills, those skills are listed in the bottom portion of its stat block. Perception is the only exception, and it appears in the top portion of the stat block whether the monster has training in it or not. For example, if a 2nd-level monster has 12 Strength and has training in Athletics, its stat block includes "Athletics +7" (+5 for skill training, +1 for the monster's Strength modifier, +1 for one-half the monster's level), assuming it has no other modifiers to Athletics.
Key Ability
The Skills table below shows the skills available in the game and the key ability for each one. A skill's key ability determines the ability modifier used when calculating a creature's skill check modifier.