Ghost Sound is one of my favorite spells. It’s a great utility spell, that can be really powerful in many situations. It can be used in combat as well as in role playing.
Ghost Sound is a level 0 illusion spell available to bards, sorcerer and wizards. Gnome Magic allows gnomes to use Ghost Sound once per day as a spell like ability. It last 1 round per caster level and produces as much noise as 4 humans per caster level. The produced sound can be virtually anything.
The usage of Ghost Sound always depends on the situation. In combat it can be used to create a distraction, may allowing your allies to land attacks of opportunity or delaying actions of your enemies. Out of combat Ghost Sound can be used to support a lie or distract guards. I gathered some examples below.
This was one of the first times I successfully used Ghost Sound. My group fought a bunch of goblins in a cave. We were out numbered, the melee fighters were completely surrounded. As I had no higher spells left I used Ghost Sound to do something. Creating the sound of 16 charging Knights in the tunnel leading into the cavern, I were able to convince some goblins, that our back up troops arrived. Most of them tried to flee allowing the fighters to get the upper hand in the fight.
To use Ghost Sound in such a way, it is important to make it convincing. Firstly the source of the sound should not be directly visible to the target. Not even goblins will believe you, if you create the sound of an charging army on an empty plane. Secondly the produced sound should fit into the surrounding. If you are in a cave use the sound of giant insects, goblins and kobolds instead of bisons. The Bestiaries provide lists of monsters for every terrain type. At last choose sounds creating fear in your enemies. The descriptions of monsters often state their enemies or fears. You might can find something by knowledge rolls.
As a gnome you can use the metamagic feat Threatening Illusion to flank a foe. The targeted field is considered as threatening enemies. The feat raises the spell level by one but a threatening Ghost Sound is still a good choice for level one spells. The effect probably will only last one round, but your rogue will thank you.
In role playing
The real strength of Ghost Sound comes into play once combat is over. The spell can be used in almost any situation.
Causing distraction is probably the most common use of Ghost Sound. It begins at the towns gate by creating the sound of a brawl to distract the guards to avoid paying 2 silver coins per feet. When you reach the market distract a merchant with the sound of fighting chickens in his cages, to allow your rogue to acquire a splendid lunch. Whenever a NPC has to be distracted, Ghost Sound is a good first choice.
Ghost Sound can be used to support your statements or to alter the attitude of an NPC. If you want to convince a NPC that the group on the next table is plotting to kill him, we will be more likely to believe you if he hears constant mumbling. The guards might help you if the bandits scream about killing guards and taking their wives. General advise: let the target hear what he wants to hear in order to support your own needs.
As Ghost Sound is a level 0 spell it is tempting to use it all the time. However keep in mind that Ghost Sound is only as effective as your game masters allows it to be. At some point the GM will snap, if you repeat the same trick over and over again. My advise: only use Ghost Sound occasionally and describe it precisely. Also explain what effect you are looking for. You won’t always get the wanted effect, but putting more effort in the descriptions makes it more likely.