Trembling horn

Trembling horn was an evocation/illusion that allowed the caster to place an invisible, magical tracer upon a person or creature. It was developed by Thyriellentha Snome for use by the City Watch of Waterdeep for use in apprehending certain individuals.

The spell was well-known among the Waterdhavian citizenry. When its effects were seen or heard, citizens often took matters into their own hands and assisted the Watch in apprehending their quarry.

Effects
When this spell was cast, a spellcaster was required to blow special horn that was associated with the Waterdhavian City Watch in the direction of affected individual while they were within sight.

Whenever the target of the spell moved within 30' (9.1 m) of another horn-carrying member of the Watch a glowing, actively sounding horn appeared over the head of the affected individual. The arcane image appeared brighter and blew louder as any City Watchmen moved closer to the affected individual. The effects faded after a matter seconds.

If an individual affected by trembling horn went for one hour without encountering any horn-carrying members of the Watch, the spell fizzled without effect.

Components
This spell required verbal and somatic components in addition to the City Watch horn.