If this were a thread about DM advice, then I would agree wholeheartedly with fudging the wording of Find Traps, or giving it a very generous interpretation. I would very much like the spell to compete meaningfully with other Level 2 spells from the same spell list.
But the nature of this thread kind of demands harsh scrutiny of wording, just like we've done with True Strike.
True Strike mechanically fails a significant portion of the time. It's a trap.
Find Traps only fails if no portion of the trap or trapped object is visible, or the DM is a d__k. If the ceiling can collapse, Find Trap detects that. If the floor has a covered hidden trap door pit trap in it, Find Trap detects that. If opening the door causes an explosion from the other side (the door being the trigger), Find Trap detects that (obviously, some DMs would rule differently on this one, but I consider that if the trigger for a trap is visible, then Find Trap detects that).
If the floor has a pit trap and there is a rug over the entire pit, then Find Trap detects that. Why? Because stepping on the wrong spot on the rug triggers the trap. Part of the trap (the rug) is actually visible.
If one wants to take the "line of sight" phrase and state that some significant portion the trap itself must be visible to the PCs "Gee, what's those weird gears over there?", then yes you are being too harsh with your interpretation. IMO.
Line of Sight just means: is there a trap in the area I can see? I definitely buy into the argument that if the entire trap is around the corner, that area cannot be seen and hence the spell does nothing. The spell is meant to check out an area that the PC can see, not a trap in the next room (again, unless the trigger for the trap is the door to the next room or some such).
In fact, the rules state something to the effect of "Usually, some element of a trap is visible to careful inspection." (and goes on to explain that). I think that most if not all of the traps listed in the DMG can be detected by this spell. Magic Statue? Check. Pit trap? Check. Poison Darts out of the walls? Check.
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