Many adventurers learn special vulnerabilities to take advantage of when attacking their enemies. Often this is through the use of pressure points or areas of vulnerability. Whether it be a duellist using precise attack, a rogue using sneak attack, a ranger attacking his favored enemy, or an elven bladedancer trained with precise strike. In order to take advantage of these special skills, a attacker must learn the weaknesses of the race he is attacking. This may be done through long hours studying ancient books, from training by others who know the secrets, or by dissecting corpses and studying their vulnerabilities.
Rules: A racial weakness can only be used against a living creature with discernable anatomy. Undead, constructs, oozes, plants, and incorporeal creatures lack vital areas to attack. A creature that is immune to critical hits is also not vulnerable to racial weakness attacks.
The attacker must be able to see the target well enough to pick out a vital spot and must be able to reach a vital spot. The attacker cannot use the benefits of racial weaknesses while striking a creature that has concealment or striking the limbs of a creature who's vitals are beyond reach.
Ranged attacks can only gain the benefit of racial weaknesses if the target is within 30 feet. You can't strike with deadly accuracy from beyond that range.
These abilities may be used with targeted spells that require a attack roll as long as the spell causes a damage range. For example, shocking grasp.
The attacker must have knowledge of a creatures weaknesses. A race automatically has knowledge of the vulnerabilities of a creature type found under their own knowledge category (thus sprytes know racial weaknesses for animals, fey, monstrous humanoids, and vermin). For all other creatures, he must make a successful level check or knowledge skill check for one of the skills below and identify a weakness. A creature that fails the check may use the healing skill on a dissected creature to try to figure out its weaknesses.
| Knowledge Skill | Creature Type |
| Arcana | constructs, dragons, magical beasts |
| Dungeoneering | abberations, oozes |
| Local | giants, humanoids |
| Nature | animals, fey, monstrous humanoids, vermin |
| Planes | outsiders, elementals |
| Religion | undead |
| Task | DC |
| Know weakness | 10 + HD of creature |
| Common monster | +0 |
| Uncommon monster | +5 |
| Rare monster | +10 |
| Unique monster | +15 or more |
Aid Other: A character may attempt to aid other using this skill, but must use a knowledge check to do so (not a level check).
Untrained Checks: An untrained Knowledge check is simply an Intelligence check. Without actual training, a character only can identify weaknesses for common creatures. The level check is not restricted to only common creatures (you get either the knowledge check or level check, not both).
Retry: No. Just as the Knowledge skill, the check represents what you know and thinking about a topic a second time doesn't let you know something you never learned in the first place. Only after increasing a rank in the appropriate knowledge skill or going up a level can you attempt a retry on the same race of creature. This retry can only be done upon encountering the race again.
Special: A confirmed critical hit acts, for that attack, as if the character knew the foes racial weakness.
Dissection using the Heal skill
Those who fail the check above may attempt to try and identify a weakness by dissection of a recently dead body and use of the Heal skill (same DC as above).
Retry: Yes. This attempt may be retried, but a new body must be examined.