My issue here is the zero cost of failure. If one player doesn't know anything about trolls, aren't they all going to say, "Can I roll?" And while that's not really a problem, the fact that it happens suggests to me that something isn't working well.
In combat, I might give them a choice: "I'll let you roll, and if you fail I'll still give you the information, but you'll miss your turn because you were thinking so hard."
Outside of combat....? I don't know; if they have proficiency maybe just give it to them?
I’d say the cost of failure is the opportunity cost. I know “you can’t try again” is not a cost for failure we would typically use, but I think in this case it’s appropriate - if you can’t remember any useful stories from Uncle Gustav, thinking harder won’t really change that. But, to keep this from being a complete “I see that I rolled a 2, why can’t I just try again?” situation, I like to treat failure on knowledge checks as progress with a setback. You will learn
something, but what you learn may or may not be directly applicable to the situation and hand.
As for the “can I try too?” effect, well, do they all have an Uncle Gustav who used to be a troll hunter? If not, then no, they can’t try too. They might try something else, but then it’s going to be a separate action, with a separate approach. Maybe one character studied trolls in wizard school, and another is an avid reader of Volo’s works. YMMV, but I don’t mind the cascade of knowledge checks if each check has a different approach and each approach gives us a little bit of new information about the characters’ histories.
Alternatively, you could say that once two or more players make the same knowledge check, it becomes a group check. It kind of makes sense, if everyone is trying to contribute information they recall from disparate sources, and not everyone’s recollection is accurate, the real challenge is in sorting out the good information from the bad. If at least half the group passes their checks, you’re able to glean something useful from everyone’s half-remembered contributions, but if more than half fail, the signal-to-noise ratio is too poor to draw any conclusions from.
Honestly I don't actually play that way. I just let the player decide. But it's my answer to people who think that what's good for the goose is good for the gander.
Fair, and like I said I think it’s an interesting suggestion!
Oh that's a hard one! How devious! (I should have known I could count on you.)
Umm.....
It seems to me that as long as a critical item (e.g. a magic item) is not the object being stolen, the stakes are not so high that it's unfair to let the thief automatically succeed. So this is not well thought out, but a couple of ideas:
- Let the players learn from an NPC that Strahd does this (maybe telling a story about it happened to this poor vampire hunter who wandered through). If they catch on and take precautions, they stop the theft. Otherwise the object is gone.
- Same as above, but with some kind of cost for staying up night.
Good answers! I have a couple of ideas for how I might handle it as well.
1. Similar to your idea that maybe this scenario shouldn’t have an uncertain outcome. Instead of using rolls to resolve this, simply narrate the spy’s failure - “In the middle of the night, you’re awoken by a noise, and open your eyes to see an unfamiliar humanoid rummaging through your pack. They freeze for a brief moment, as their fight and flight instincts compete for dominance. What do you do?”
2. Give the player something to interact with. Narrate some indication that the character keeping watch notices, such as the sound of a twig snapping, or a shadow moving between the trees. Let the player of the character keeping watch respond as they will, and adjudicate their actions accordingly. This is basically the equivalent of telegraphing.
3. Kind of cheating here, since I said “without relying on passive checks” in my original framing of the scenario, but to my mind, keeping watch while your allies sleep is an action performed repeatedly over time, so I do think this is an appropriate case in which to have the lookout make a passive Wisdom (Perception) check.