Knowedge (Int; trained only)

    You are educated in a field of study and can answer both simple and complex questions. Like the Craft, Perform, and Profession skills, Knowledge actually encompasses a number of different specialties.

     Many Knowledge skills have specific uses and areas of expertise as noted below.

• Arcana (ancient mysteries, magic traditions, arcane symbols, constructs, dragons, magical beasts); 5 or more ranks of Knowledge (arcana) gives a +2 synergy bonus to Spellcraft checks.
  
• Dungeoneering (aberrations, caverns, oozes, spelunking) 5 or more ranks of Knowledge (dungeoneering) gives a +2 synergy bonus to Perception checks when looking for traps.
  
• Engineering (buildings, aqueducts, bridges, fortifications); This is the most important skill with regard to technological subjects.  Knowledge (engineering) can be used to identify a golem’s abilities and weaknesses.  Knowledge (engineering) is also used to identify and understand unknown technological objects in a similar manner to how Spellcraft is used to identify the properties of a magic item.  The DC to correctly identify and understand an unknown technological object is equal to the object’s Craft DC.  An object with a Craft DC of 15 or less can be automatically identified and understood by someone trained in Knowledge (engineering) who also has the Technologist feat.  5 or more ranks in Knowledge (engineering) gives a +2 synergy bonus to Disable Device checks.
  
• Geography (lands, terrain, climate, people); Used for astronomy.  5 or more ranks in Knowledge (geography) gives a +2 synergy bonus to Wilderness Lore checks.
  
• History (wars, colonies, migrations, founding of cities)  5 or more ranks in Knowledge (history) gives a +2 synergy bonus to Linguistics checks.
  
• Local (legends, personalities, inhabitants, laws, customs, traditions, humanoids) 5 or more ranks in Knowledge (local) gives a +2 synergy bonus to Diplomacy checks when gathering information.
  
• Nature (animals, fey, monstrous humanoids, plants, seasons and cycles, weather, vermin) 5 or more ranks in Knowledge (nature) gives a +2 synergy bonus to Handle Animal checks.
  
• Nobility (lineages, heraldry, personalities, royalty) 5 or more ranks in Knowledge (nobility) gives a +2 synergy bonus to Diplomacy checks (other than when gathering information).
  
• Planes (the Inner Planes, the Outer Planes, the Astral Plane, the Ethereal Plane, outsiders, planar magic)  5 or more ranks in Knowledge (planes) gives a +2 synergy bonus to Use Magical Device checks.
  
• Psionics (psionic traditions, psionic symbols, psionic creatures including psionic dragons, psionic constructs, and psionic beasts); 5 or more ranks gives a +2 synergy bonus to Auto Hypnosis checks.
• Religion (gods and goddesses, mythic history, ecclesiastic tradition, holy symbols, undead) 5 or more ranks gives a +2 synergy bonus to Turn or Command Undead checks.
  

GENERAL KNOWLEDGE

Check: Answering a question within your field of study has a DC of 10 (for really easy questions), 15 (for basic questions), or 20 to 30 (for really tough questions).

Action: Usually none.  In most cases making a Knowledge check doesn't take an action.

Retry: No.  The check represents what you know, and thinking about a topic a second time doesn’t let you know something that you never learned in the first place.  May retry once more ranks are gained.

     Some typical Knowledge skill check DC's, and the Knowledge skill associated with them, are listed below:

MONSTER LORE

     You can use this skill to identify monsters and their special abilities and vulnerabilities.

Check: In general, the DC of such a check equals 10 + the monster’s CR.  For common monsters, such as goblins, the DC of this check equals 5 + the monster’s CR.  For particularly rare monsters, such as the tarrasque, the DC of this check equals 15 + the monster’s CR or more.  A successful check allows you to remember a bit of useful information about that monster.  For every 5 points by which your check result exceeds the DC, you recall another piece of useful information.

KNOWLEDGE UNCHAINED

     By taking the Signature Skill feat, you can unchain the following special bonuses:

• 5 Ranks: When you successfully identify a creature, you gain one additional piece of information for every 5 ranks you possess in that Knowledge skill.
  
• 10 Ranks: When you successfully identify a creature, you gain a +1 competence bonus on attack rolls, opposed ability checks, skill checks, and caster level checks against creatures of that kind (e.g., glabrezu demons, but not other demons or evil outsiders) for 1 minute. This bonus increases by 1 for every 5 ranks beyond 10 you possess in that Knowledge skill.
  
• 15 Ranks: When you fail a Knowledge check, you can reroll the check at a –10 penalty. The competence bonus above also applies to saving throws against exceptional, spell-like, or supernatural abilities used by creatures you identify.
  
• 20 Ranks: Whenever you attempt a Knowledge check, you can roll twice and take the better result.