Each investigator has five different skills listed on the bottom of his Investigator sheet. The number below each skill is the number of dice investigator rolls when resolving a test. Each skill is represented with unique icon.
- Lore is often tested when casting Spells and resolving Other World Encounters.
- Influence is often tested when performing Acquire Assets action and resolving General Encounters on City spaces and Defeated Investigator Encounters.
- Observation is often tested when resolving Research Encounters and Expedition Encounters.
- Strength is often tested when resolving Combat Encounters and Expedition Encounters.
- Will is often tested when resolving Combat Encounters and Other World Encounters.
The value of each skill represents the base number of dice the investigator can roll when testing that skill.
When an effect allows an investigator to improve a skill, he gains an Improvement token with the matching icon and places it below his Investigator sheet with the "+1" side up. If he improves that skill a second time, he flips that token to the "+2" side. An investigator's skill is equal to the value printed on his sheet plus the value of the matching Improvement token. An investigator cannot improve a skill to more than 2 of its original value.
With the introduction of the Under the Pyramids expansion, impairing of skills is also possible. If a skill is impaired, place an impairment token with the matching icon on the investigator sheet with the "-1" side up. If the skill is impaired further, flip the token to the "-2" side. Like with skill improvements, an investigator cannot impair a skill to less than 2 of the original value.
Skill Bonuses vs. Skill Values
A skill bonus is an effect which will state "Gain +# [Skill]", or "Gain +# to all skills". Skill bonuses are applied only when performing a test. Only the highest skill bonus from a single effect can be used during each test, meaning that you cannot gain bonuses from mulitple sources simultaneously. Skill bonuses are often also conditional. The most common condition is "during Combat Encounters", which as the description implies, the skill bonus will only apply during Combat Encounters and not during any other test of that skill.
A skill's value is sometimes referenced in an effect. For example, Harvey Walters' component action allows him to improve an ally's skills as long as their skill value is equal to or lower than his skill value. When determining a skill's value, only impairment and/or improvement tokens are taken into account in addition to the investigator's base value. This means that skill bonuses never affect a skill's value.
- "+/- 2" tokens must be treated as two separate "+/- 1" tokens for all intents and purposes. (e.g. You cannot remove a -2 impairment token if an effect states to remove 1 impairment token of your choice; you would instead flip the token to the -1 side.)
- Despite the original wording in the Eldritch Horror rulebook, you can improve or impair a skill more than twice every game. This is mostly the result of that skill being impaired, in which case you can improve that skill to get rid of the impairment token. In this way, you can infinitely impair and/or improve skills, but never to more than or less than 2 of its original value.