I know, I know, D&D Next has been announced, 4e is dead, and no one wants to read another personal trip report when there are new editions to design! But I'd been meaning to do a write-up inspired by my party's second session in the Tomb of Horrors and some recent posts by Robert J Schwalb touched on the topics enough that I felt like I should actually write them out.
So to recap, I'm taking a group of five intrepid adventurers trough the 4th Edition re-release of the classic Tomb of Horrors. The party has made it through some rather insidious hazards by this point (which I won't spoil) and are in the depths of the dungeon. This session there was a little bit of combat, but for the most part skill checks and scene interaction dominated. Here are some observations:
Close Can be Good Enough
If a player wants to do the right thing with the wrong skill in a believable way, let them.
Listed skill checks in dungeon descriptions ("Detectable with an Arcana/Perception Check" etc.) serve as a great hook for the DM to let the player interact with the environment; however, they shouldn't be taken as the upper bound of what players can do. Instead, these sort of details should be treated a kind of high level approximation of the scene from which the DM can extrapolate. Keep in mind that the skill system in D&D is very loose, and when it comes to ad-libbing interaction there can be a fair amount of overlap and vagueness in what is covered by one skill versus another. Detecting a vast unholy aura on an alter might be a clear Religion check, but maybe an Arcana check looking for the same thing would work as well. Or perhaps a Nature check would work as well as a Dungeoneering check for detecting a secret door in a cave wall (or maybe even a Perception check, to notice a faint breeze blowing strangely into the dungeon).
Feel free to adjust DCs here (widely, even) if a skill is related but not exactly right. Achieving something through an indirect means is going to be harder than looking for exactly the right thing. However, so long as a player provides a reasonable justification for what they want to do, you should let them try. And if they try something that seems like a stretch, but succeed exceptionally, maybe they deserve at least a clue to the right approach if not an outright success.
Specific is Better than General
Make DCs easier if the players are looking for something exactly the right thing, and make it more challenging if they're just "fishing"
Finding a secret door in a large room is going to be a lot harder than seeing if there is a secret passage underneath the Alter of Unmistakable Evil. Whenever possible, I never let my players say "I want to make a Perception check" -- I always try to coax them on a little by saying "what are you looking for?" or "where do you want to focus your attention?" This is important from a story-telling sense because it helps the players build the illusion that they're exploring this imaginary space and using the game as just a framework, instead of just playing with dice. It's also helpful for the DM because it lets them flesh out an environment and keep the player more engaged by revealing details in response to their interactions, instead of just reading off a big monologue at the start of every room.
Of course, if you're not careful this can result in your players wandering around in frustration looking for the right widget to manipulate. This leads into the next point...
Fail, but Fail Interestingly
Try not to let players fail skill checks that keep the adventure from moving forward.
This comes back to a point I made in my old post about Skill Challenges, where every check has to have some kind of viable consequence for either passing or failing. Sometimes a little bit of frustration and befuddlement is desirable, but players get bored fast and you need to move the story forward at some point.
To this end, consider dropping hints to guide players along. If they fail a check, give them options for how to give themselves a modifier to trying again, or a second related approach that might be successful. Or, if they try something that doesn't fit what's listed in the adventure and succeed, give them hints on what the areas of interest actually are.
Again, you don't need to railroad characters one way or the other; however you should always try and reward them trying new things whenever possible. Sometimes even walking into traps can reveal a bittersweet benefit.
A Natural 20 Always Succeeds
Always. Just make it work.
Personal preference, of course, but d20 is inherently a swingy game, and sometimes that means unlikely successes in the face of ridiculous chance. If the barbarian tries to bash the dimensional portal with his hammer and he rolls a critical hit, perhaps he collapses the pillar supporting the arch. Or at Paragon/Epic level, perhaps the force of his hammer smashes the tear in space closed. I dunno, just do it. Your players will love it, and everyone will remember the scene.