Something is moving, just out of your vision... Is that a cloud of mist?
Type: magical; Perception DC 30; Disable Device 30
Trigger location; Reset None
A Fey Mister is a device that is partly in this world, and partly in the Fey Realms. It darts around, and sprays a fine mist on unsuspecting interlopers when they wander into someplace that the fey denizens would prefer them not to be. When sprayed, PCs end up partly in the Fey Realms. They will see and hear Fey Realm Ghost images, and even have slight physical interaction. This translates into sensory and other penalties. Fey Mister (DC 22 Will Save or become entwined in the Fey Realms for 9 hours; multiple targets(all targets in a 30' cone).
If any PCs are affected by the mist, you can play up the environment. Describe fleeting images that appear in their peripheral vision, and vanish when they look at them. Explain that every now and then, they step in an invisible hole or brush against something that is not there when they look a second time. You can make it sound to the PCs as if they have entered a haunted area.