Alarm (Clairsentience)

Base(s): Clairsentience
Usage: set-alarm(scene, R) -> radius=M alarm : t=8•hr -> psv(Perception)
Description: Set a boundary around you that warns you when it is crossed by anyone with hostile intent.

While you sleep, there is a bubble around you with radius up to your modifier in metres. When any creature with hostile intentions crosses that barrier, you will get a passive Perception check as if you were awake. Succeeding in that check will result in you waking. You may then make a standard Perception check, upon waking, and before any actions by that creature.