Alarm that calls monsters.Final Fantasy IV description
Siren is an item that forces the player into a battle with the rarest enemy group in the current map. It can be found in the Giant of Babil, Cave of Trials, and the Lunar Ruins (as part of the Mech Set), dropped from Tunneler (2D and 3D), Arachne (2D and 3D), Alraune (2D and 3D), Security Eye (2D only), Searcher (2D and 3D), Green Dragon (2D and 3D), Yellow Dragon (2D and 3D), and stolen from Security Eye (2D only), Searcher (3D only). In the 3D remakes, it can also be obtained by completing the Lunar Path West and East maps (x3 each) and Lunar Subterrane B5 map (x3), or bought for 3,000 gil at the Hummingway Home.
Siren is an item that forces an encounter with rarest formation and group.
Siren is a dummied item would have automatically sent the player into a battle.
Siren is an item that can only be used in Quest Medleys. It summons fearsome foes to the next Battle Music Sequence the player can reach. It can only be used once per Chaos Map. It can be obtained randomly after completing a Music Stage.
In Final Fantasy XV, the player can use the "monster whistle" to spawn enemies at the nearest spawn spot.