Knowledge Skills
Something got me thinking last night and I thought I would be better off doing a little commentary on it.
It comes down to an issue with in-character knowledge. We have always played with knowledge skills being able to give you interesting background and sometimes monster info. When WotC revised the game in 3.5, they included a mechanic to handle monster knowledge. Please take a few minutes to look up the knowledge skills under 3.5. You may notice that there are specific mechanics in there to handle knowing anything about specific types of monsters. These mechanics are important because it provides more mechanical value to the people that choose to spend skill points in knowledge skills.
If you do not have ranks in the appropriate skill, then you have no chance of knowing anything about a specific monster until you gain in-game experience with it.
A classic example would be Trolls. As players, you are familiar with a troll's regenerative abilities. You also know that fire and acid bypass a troll's regeneration. However, your PC's may not have this information. If you do not have ranks in Knowledge (Nature), then you are not able to even try to Knowledge (Nature) roll to know anything about a troll. Well, except that it is big and green and ugly. If you do have ranks in the skill, then you can try a Knowledge (Nature) check when you encounter a troll and see what it is your PC might know.
This is an important component of the Roleplaying aspect of the game. You need to be able to roleplay the ignorance your PC might have. If you don't like that component of ignorance, you might consider allocating some skill points to knowledge skills and hope you consistently roll well.
Another example would be the lycanthropic Damage Reduction, and the fact that silver can bypass it. Without the appropriate knowledge skill, or somebody knowledgable conveying this information to you, then your PC's don't know that. (As an aside, within the campaign worldview, lycanthropy falls under Knowledge (Nature). Other shapechangers might fall under a different category though.)
Unless you have Knowledge (Religion), you are going to have a hard time identifying the best way to beat a vampire. Without Knowledge (The Planes), you are going to have a difficult time with angels, demons, devils, daemons, etc. In fact, you might not even be able to tell the difference between some of them.
Without Knowledge (Arcana) you probably won't know that the dog you just saw was a Blink Dog instead of a wild mongrel.
There is a line between player knowledge and PC knowledge. You can certainly ask around to see if people can tell you things about monsters, but you might not want to rely on rumor and myth. For a lot of commoners, a lot of these creatures are simply unbeatable. Even something as lowly as DR 5 will make it very, very difficult for the normal person to do any damage if they have fought one of these creatures. If you want your PC to have real, valuable knowledge on odd creatures, then you need to take ranks in knowledge skills. Otherwise, you won't have any idea if a wild rose will have any affect on a vampire. Nor will you realize that daylight is any more harmful to a vampire than it is to a zombie or skeleton. Unless you learn that when you are actually fighting one.
Now, using player knowledge (metagaming) to drive the decisions and actions of your PC can have repercussions. I may decide to deny some of your exp that session. I may decide to houserule a monster (or even a type) so it has different vulnerabilities, or I may come up with another solution. It's not so much a matter of punishing anyone. It's an issue of making sure people receive "fair value" for their skills. If one PC has spent skill points on Knowledge (The Planes), but nobody else has, it is not fair to let somebody else pull out their silvered weapon when they encounter a devil because the player knows it will be more effective then their +2 flaming weapon. The PC who has the skill gets to make the skill check (or blow it) and then share whatever information is known with the group.
