Well, sooner or later most normal adventuring parties are going to meet skeletons, and trolls, and werewolves, and all sorts of other creatures that have specific weaknesses. Part of the challenge-mitigation is that weakness, which means in theory these creatures *should* be more of a challenge when met for the first time.
Lanefan
But met for the first time by whom?
This discussion has come up many times, and I admit that in the distant past I felt much the same way. But I will ask my question again:
In a world where civilization has fought back trolls, skeletons and werewolves, for thousands of years (or in the case of the Forgotten Realms,
tens of thousands of years), is there any person on the planet that would not know trolls are vulnerable to fire and lycanthropes vulnerable to silver? Descriptions of most towns have silvered arrows in their armory for just such a purpose, for example.
Having said that, D&D is a role-playing game. While many people equate role-playing to acting, it's really simply making decisions and taking actions in character. Instead of reacting to this situation as I would, how would this character react?
For most things, we have rules that help set limitations. The wizard doesn't know how to use a great sword. He can pick one up and swing it around, but if he tries to attack with it, he's at a bit of a disadvantage. Knowledge, though, is trickier. How do we know what a given character knows or doesn't know?
We have to metagame it. Yes - deciding that they don't know how to kill a troll is as much metagaming as deciding that they do. The reality is, for an individual player, however they want to determine what their character does or doesn't know is almost entirely up to them. 99% of the game that's what a player is doing. The problem arises only when somebody else (the DM or another player) decides that they don't like the decision that another player has made.
The real problem then, is not metagaming. We have no choice but to metagame. The problem is identifying the limits of character knowledge, and how that is acted upon in the game.
For many people there is no problem - they character knows what I know. Of course, there are times the character knows something you don't know, and we have ability checks to help with those circumstances. The reality is, the game has rules for that as well. It's the DC of the information at hand. I think that knowing a troll is vulnerable to fire is (very) common knowledge. If it's common, then pretty much nobody has to make an ability check to know it. The DC is that low.
But I think every player, whether they acknowledge it or not, restricts the knowledge of the character. That is, they role-play that the character doesn't know something that they as a player does. You might know calculus, or the recipe for gunpowder, or perhaps you're a surgeon, but I think it's rare for any player to suggest that these are things that their character also knows.
And while it may not be obvious in the discussion, the real question is where that threshold is, and how it's handled by the player/group.
My groups tend to self-limit, often to more of an extreme that I think. So they might ask me if their character would know something in particular. In most cases I think the answer is yes, but occasionally not. If no, then how do you (as a table) expect that to play out? Some people enjoy the challenge, other don't. Those that don't like the challenge tend to have a higher threshold for what a player might know that a character doesn't.
I, as a DM, prefer to approach it largely from a different direction. I encourage my players to know the rules, and also to read the Forgotten Realms releases, whether it be novels, sourcebooks, whatever. Why? Because my goal at this stage is better immersion. Make the world feel like a real place. The more common knowledge that the players share about the world and its inhabitants, the more real the world feels. The published material is the backdrop for our campaigns. I do make a lot of changes, including to monster abilities and such. Although it's not so much so they won't know, as it is that I just see the monster differently than published.
We even go so far as to make it a general rule that when the party is split up, that all of the players remain at the table and listen to the encounters under the assumption that the characters would tell the rest of the party what happened and it saves us time. Plus, if there are clues that occur, having them relay what happened to the rest of the party is rarely sufficient. If there is something that needs to be secret (for a time), then I'll take the relevant people aside, or use a note, or some other way to actually keep it a secret from the other players.
Back to this quote, if the challenge of a "secret" weakness is only a challenge for the first encounter with such a creature? Then what's the point? I don't worry about trolls susceptibility to fire as a plot or challenge point in the course of the game from a knowledge standpoint. It's a challenge from a resource or tactic standpoint. Just like when Jon Snow arrives at the wall, he doesn't have to discover that you should burn the dead. But it has an impact - in part because even though he knows that, there are times when they can't do that for one reason or another. Knowing what will happen actually makes it worse.
I approach it from the opposite perspective. If everybody knows trolls are vulnerable to fire, why hasn't the militia or guard been able to root out all the trolls and burn them? Could be for a variety of reasons, but here's one suggestion. Trolls live in swamps. Why? Because the fire isn't effective against them there. Sure, it might slow, or even prevent some of their regeneration, but you can't burn the whole troll in the swamp. Maybe it just doesn't work against a wet troll without at least 2 rounds of continuous application. Even better, let's say you sliced off the arm of a troll with a flaming sword. If the entire troll needs to be burned, then all you've done is prevented the troll from regrowing that arm. Oh, and the arm that dropped into the swamp can't regrow another troll. But that arm, now hidden beneath the brackish waters, isn't dead either. Suddenly you find yourself being tripped by a troll arm, and being drowned at the same time you're being attacked by the troll itself.
The point is, you start with the idea that everybody already knows a given creature's weakness, but circumstances have created a scenario where you can't take advantage of that weakness. That makes for an interesting encounter. Because instead of the players trying to determine when and how the characters would figure it out, it creates a problem for the players to figure out.
I think most of us would agree that actually figuring out a challenge is
more fun than pretending that the character figured it out.
