Like the Craft and Profession skills, Knowledge actually encompasses a number of unrelated skills. Knowledge represents a study of some body of lore, possibly an academic or even scientific discipline. Below are listed typical fields of study. With your DM’s approval, you can invent new areas of 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).
Analyzing Creatures: In many cases, you can use this skill to identify monsters and their special powers or vulnerabilities. In general, the DC of such a check equals 10 + the monster’s HD. 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.
Remember, you must have ranks in the appropriate Knowledge skill for a particular monster’s type. For example, you can’t use Knowledge (arcana) to identify a mohrg, since that creature is of the undead type, and undead creatures require Knowledge (religion) to identify.
Action: Usually none. In most cases, making a Knowledge check doesn’t take an action—you simply know the answer or you don’t.
Try again: 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.
Synergy: If you have 5 or more ranks in Knowledge (arcana), you get a +2 bonus on Spellcraft checks.
If you have 5 or more ranks in Knowledge (architecture and engineering), you get a +2 bonus on Search checks made to find secret doors or hidden compartments.
If you have 5 or more ranks in Knowledge (geography), you get a +2 bonus on Survival checks made to keep from getting lost or to avoid natural hazards.
If you have 5 or more ranks in Knowledge (history), you get a +2 bonus on bardic knowledge checks.
If you have 5 or more ranks in Knowledge (local), you get a +2 bonus on Gather Information checks.
If you have 5 or more ranks in Knowledge (nature), you get a +2 bonus on Survival checks made in aboveground natural environments (aquatic, desert, forest, hill, marsh, mountains, or plains).
If you have 5 or more ranks in Knowledge (nobility and royalty), you get a +2 bonus on Diplomacy checks.
If you have 5 or more ranks in Knowledge (religion), you get a +2 bonus on turning checks against undead (see Turn or Rebuke Undead).
If you have 5 or more ranks in Knowledge (the planes), you get a +2 bonus on Survival checks made while on other planes.
If you have 5 or more ranks in Knowledge (dungeoneering), you get a +2 bonus on Survival checks made while underground.
If you have 5 or more ranks in Survival, you get a +2 bonus on Knowledge (nature) checks.
Untrained: An untrained Knowledge check is simply an Intelligence check. Without actual training, you know only common knowledge (DC 10 or lower).
The absolutely crucial tasks of navigation and piloting fall under the description of Knowledge (geography). While Profession (sailor) covers the maneuvering and handling of a ship, the science of navigation requires a distinctly different set of training—mathematics, geometry, optics, and astronomy, among other fields.
Navigation revolves around two basic tasks: course setting and piloting.
Course Setting: When you set out on a voyage, you need to know how to get where you’re going. The difficulty of setting an accurate course depends on the quality of information you have about where you’re going.
The DM makes this check for you, since you don’t know for certain if you have planned an accurate course.
| Close and very familiar | DC 5 |
| Distant and very familiar | DC 10 |
| Close and studied carefully | DC 10 |
| Distant and studied carefully | DC 15 |
| Close and seen once | DC 20 |
| Distant and seen once | DC 25 |
| Close but uncertain | DC 25 |
| Distant and uncertain | DC 30 |
| Mythical or legendary | DC 35 |
| Start point well known | +0 |
| Start point uncertain | +5 |
| Start point only guessed at | +10 |
| Start point completely unknown | +20 |
| Excellent chart | +2 |
| Poor chart | –2 |
| Extremely poor chart | –5 |
| False chart | –10 |
You make a course setting check when you begin a voyage, and anytime you realize that you have gotten lost and need to determine a new course to follow to reach your destination.
If you fail your course setting check by 5 or less, you arrive in the vicinity of your destination; for close voyages, you miss by 5d10 miles; for voyages to distant points, you miss by 5d100 miles.
If you fail your course setting check by more than 5, you are wildly off course. On a close voyage, you miss by 10d10 miles; on a long voyage, you miss by 10d100 miles.
Piloting: Piloting is the art of not getting lost and determining where you are in relation to your intended course, so that you can make corrections as necessary. Piloting actually involves a variety of related techniques: celestial navigation, dead reckoning, and true piloting—using landmarks on shore to establish your position.
Each day of your voyage, you make a piloting check to establish your position and make the routine corrections necessary to hold to your intended course. The DC of this check depends on the methods available to you; on open ocean with cloudy skies, you have no landmarks and no celestial bodies to observe.
| Very familiar coast in sight | DC 5 |
| Coast studied carefully in sight | DC 8 |
| Coast seen once in sight | DC 13 |
| Unknown coast in sight | DC 15 |
| Open ocean, clear weather | DC 17 |
| Open ocean, poor visibility | DC 25 |
| Open ocean, stormy weather | DC 30 |
| Open ocean, gale or hurricane | DC 40 |
| One previous missed check | +2 |
| Two previous missed checks | +5 |
Failing your piloting check once is not a problem; you simply failed to establish your location for the day. You can go back to your previous day’s established position and estimate your current position given the course and speed you think you’ve followed since. You do not become lost until you fail your piloting check on three consecutive days.
Being lost at sea is much like being lost on land; see Getting Lost for details.
Source: Player’s Handbook (version 3.5), page 78, with supplementary material marked in text. Added “lycanthropes” to the Knowledge (nature) subject list.
Knowledge does not possess an epic usage.