invisibility alarm
Class: bard : 1 inquisitor : 1 ranger : 1 mage : 1
Syntax: cast CLASS invisibility alarm

You draw an invisible alarm rune on the ground. If an alarm detects anyone hidden or invisible in the room but you and your followers it will convey a telepathic message directly into your mind. You can have as many alarms as you need, but after a while the magic in them will dissipate.