Alarm that calls monsters.
Siren is an item that forces the player into a battle with the rarest enemy group in the current map. It cannot be obtained in the SNES or PlayStation versions, but can be found in the Giant of Babil, Cave of Trials, and the Lunar Ruins as part of the Mech Set, won from Tunneler, Arachne, Alraune, Security Eye, Searcher, Green Dragon, and Yellow Dragon, and stolen from Security Eye and Searcher in the Game Boy Advance and later 2D versions of the game. In the 3D remakes, it can also be obtained by completing the Lunar Path West and East maps (x3 each) and the Lunar Subterrane B5 map (x3), or by buying it for 3,000 gil at the Hummingway Home.
Siren returns as an item that functions identically to its previous version.
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.
Sirens are from Greek mythology. In the story of Odysseus, the Sirens are beautiful women who lure sailors with their voices. Odysseus escaped the Sirens by having all his sailors plug their ears with beeswax. He was curious as to what the Sirens sounded like, so he let himself be tied to the mast to ensure he could not fall victim to their voices.
- In Final Fantasy XV, the player can use the "monster whistle" to spawn enemies at the nearest spawn spot.