Let's say there is a room description in a module that says "There is a swinging blade trap in the fireplace mantle. Anyone searching the fireplace must make a save..."
How do you (anyone, not just Scribe) turn that into a "player skill" situation?
The way to challenge the player as opposed to challenging the character with traps is to make the detection and disarming of the trap a matter of the player paying attention to the description of the environment, making reasonable deductions based on that description to determine the presence of the mechanism, and interacting with it via narrative description of their character’s actions.
So, in the example of the spinning blade trap in the fireplace, you first need to make it possible for a player to reasonably deduce the presence of such a trap based on the description of the environment. There are a few ways you might go about this. For one, you might include in your description of the room some telegraph indicating it. For example, maybe you point out that the fireplace is completely bare of wood, ash, or soot, but is thick with dust and cobwebs. This could hint to the player that the fireplace has neither been used nor cleaned in a long time (because occupants of the space know about the trap). That might be too subtle, particularly if the players have never encountered a trapped fireplace before, so if you want to be a bit more obvious, you might note an un-mortared brick or section of bricks in the fireplace floor to hint at the presence of a pressure plate, and/or a seam along the interior to hint at where the blade swings out from. Some or all of these telegraphs could require a certain passive Perception score to detect, if you’re the sort who likes to include a mix of challenging the player and challenging the character. Though, if you go this route, I strongly suggest including at least one unmissable telegraph, because a trap that gets sprung with zero telegraphs tends to feel like more of a “gotcha” than one that is at least somewhat telegraphed.
Alternatively, you could lay the groundwork earlier in the dungeon, including another identical trap that has previously been sprung and not reset. This lets the player know well in advance that this is a type of trap that exists in the dungeon and they should be on the lookout for. In general, the more the players have been exposed to a certain type of trap, the less telegraphing you have to do for them to have a reasonable chance of noticing it. If you have a dungeon with tons of fireplace traps, after like the third such trap, players are going to be cautious around every fireplace they see in the dungeon, and maybe in other dungeons too.
Of course, detecting the trap is just the first hurdle. Disabling or otherwise mitigating it can also be a challenge for the players, if you give them enough information to make reasonable attempts at interacting with it. This, in my approach, also extends to when checks do become necessary. As I talked about earlier, telling the player what they have to roll before making them commit to actually rolling helps close the information gap between the player and their character, and gives the player the opportunity to feel like they’re choosing to take (or choosing not to take) a calculated risk, rather than asking for a skill check and hoping their bonus is high enough to eke out a success whatever they roll.
And, even in the case that the players totally miss the trap and have to make that saving throw, you can introduce an element of challenging the player to that too, if you’re so inclined. Rather than just calling for the save and applying the results immediately, you can narrate one last telegraph about what their character notices in that split second between triggering the trap and potentially getting hit by it, and letting them respond. For example, “as you lean into the fireplace to investigate, you feel a brick sink slightly beneath your weight, and hear a metallic grinding coming from your right. What do you do?” Then, depending on what the player does, you might give them advantage on their saving throw, or even allow them to succeed automatically on it. Alternatively, maybe they do something counterproductive and get disadvantage or automatically fail.
It’s all about making the player feel like they’re making informed decisions (which may or may not require the roll of a die to determine the outcome of), rather than choosing what stats they want to add to a roll they have to make in order to accomplish anything.
