SWAN SONG DEFINITION BY WIKIPEDIA :
The phrase "swan song" is a reference to an ancient belief that the Mute Swan (Cygnus olor) is completely mute during its lifetime until the moment just before it dies, when it sings one beautiful song.
Furthermore :
By extension, "swan song" has become an idiom referring to a final theatrical or dramatic appearance, or any final work or accomplishment. It generally carries the connotation that the performer is aware that this is the last performance of his or her lifetime, and is expending everything in one magnificent final effort.
And there's also some Swan Song references in novels, like the famous mystery novel And Then There Were None by Agatha Christie that includes a gramophone record titled "Swan Song." When played, it accuses the houseguests and servants of murders that, for various reasons, they were not punished for. The killer intends to punish the wicked as a final act.
Another novel by Robert R. McCammon simply titled Swan Song tells the story of a young girl in a post-apocalyptic world who will be the savior of the human race.
Some creeptastic songs with this swan reference also exist.
OH THIS HAS NO HIDDEN MESSAGE ET AAAALLL. (sarcas intended)
Make what you will with all those reference meanings. I think it just means this,
this scares me but also means that the finale will most likely be full of awesomesauce,
Super and Natural **MissTee
