The caster picked an area of no more than 20 ft (6.1 m) wide that when crossed by a creature the spell would alert the caster. When casting the spell, the caster could choose what creatures would not trigger the alarm. The alarm itself was a "ping" in the mind of the caster that would wake them if they were asleep.
- ↑ 1.0 1.1 1.2 1.3 Mike Mearls, Jeremy Crawford (2014). Player's Handbook 5th edition. (Wizards of the Coast), p. 211. ISBN 978-0-7869-6560-1.
- ↑ David "Zeb" Cook (August 1989). Player's Handbook (2nd edition). (TSR, Inc.), p. 131. ISBN 0-88038-716-5.
- ↑ Jeff Grubb and Andria Hayday (April 1992). Arabian Adventures. (TSR, Inc), p. 152. ISBN 978-1560763581.