I'm running a megadungeon campaign, APL12. The NG Elf U-Rogue (Scout)12 in the party has a Perception +28 at this point so when she is ahead of the party searching for traps only the most high level spell traps matter. The PCs however have gotten so used to moving slowly but finding nearly everything along the way that none of them, not even the rogue has any sort of permanent Detect Magic going or magic items like a Gem of True Seeing.
This got me thinking: couldn't this party be tripped up by a simple Alarm spell? I'm not talking about a Proximity Trigger as part of a trap here, just a L1 spell cast by, say, an enemy wizard. The spell isn't called out as a spell trap and if it isn't part of a larger trap as the trigger mechanism, the only way to detect it in place is by magic right?
