Schadrach

Detect Magic telling someone “it’s chowder” is a cop-out, same as a DM saying “you failed the skill check because you looked suspicious.” If a spell exists to reveal a magical aura, use it to reveal an aura, not to sass the player.

My answer in that case is “You detect no aura” from the non-magical chowder (or maybe they do detect one if it was flavored with prestidigitation), unless it’s an edition where the effect is a cone, and they are sitting across the table from their friend blinged out in magical gear, in which case they are definitely detecting an aura. Several of them. And they’re going to have to take time, focus, and make checks to recognize that none are coming from the chowder.

Paranoia, the game where every character is technically engaged in a crime punishable by death at basically all times, and you’re given a number of clones because you are expected to die…a lot. Also the R&D gadgets, like the personal disintegrator which does exactly what it says on the tin - disintegrates your person.

Like forcing the players into an encounter where all their toolkits are nerfed. Close quarters for casters, magical monsters that can’t be harmed by melee, or NPCs that are way OP for the group and they stick to the Monster Manual to the letter.

When I GM, it depends on just how narrow and just how powerful your particular toolkit is. I’m not going to ensure that you can do whatever your thing is at absolutely every opportunity, and if your schtick becomes well known, enemies capable of planning will plan around it when feasible. The more narrow your schtick is, the more scenarios you might encounter where it does not apply simply by chance (for example, if you’re a flying archer every room in a dungeon won’t gain a minimum 30’ high ceiling to maximize your use of that). The more disproportionately powerful your schtick is compared to other party members, the more likely I am to specifically come up with occasional scenarios meant to make it not apply so someone else gets to shine.

Sometimes I will signpost something is a very bad idea, and if you do it anyways (or do something else absurdly dangerously foolish) I’m not going to pop up a guard rail to save you at the last moment - retrieving your body from somewhere adrift on the astral and your soul from the gemstone the archdevil you pissed off is keeping in his treasury to try to save you is the next adventure hook.

You encounter a huge, elaborate tome, on a concealed lectern, in a library connected by a hidden door directly off the bedroom of a powerful wizard, you detect magic and get extremely powerful auras of conjuration, transmutation and evocation maybe “I flip it open to a random page and start reading aloud, I’ll sound out any words I don’t recognize” is not, in fact, a wise decision. The copy of “Words You Mispronounce And Die: A Primer For Apprentice Wizards” you saw on one of the shelves on the way there, the references to a cursed grimoire of terrible power, the book being bound in the skin of an angel covered in burns and scars, etc, etc should have maybe hinted at that.

Doesn’t need to be a sole cause to be a cause. See cancer, where smoking causes lung cancer, but not all lung cancer is caused by smoking. But again, needs more study.

Eh, it’s not totally baseless. Hell, there’s even a non-zero chance it’s true. It’s way too early to claim it as true though, since studies on the topic are few, have mixed conclusions and correlation is not causation. I refuse to give it any more credence than “not totally baseless” though.