My lovely Luna sent me the song
Aviary by Ego Likeness. I am listening to it on obsessive-repeat.
The story shaping in my head is a Fire Nation play, written pre-Conquest but rarely performed due to the requirements of the leading lady to be able to waterbend and several significant other characters needing to be able to firebend. Written pre-Conquest, and now being performed again after Sozin's Comet.
In this scene, the Water Tribe Avatar has gone into the Spirit World (to chase down her stolen lover? to find someone to teach her firebending?) and she has stumbled across a forest full of spirit-birds. Said spirit-birds attack her and cause her much damage, leaving her half-dead.
As the attack goes on, there is a singer sitting in darkness on a high 'branch', singing this song. Then after the verse about the black birds, the light shines on the singer, revealing the dying Firebird. She descends on her own verse and chases away the other spirit-birds. She also seriously gets her sultry on as she gathers up the Avatar.
Whoever designed the Firebird's costume definitely used Ozai's Phoenix King robes as the basis. Except without the dorky helm.
Reference ReferenceOf course, the Firebird's robes are ragged and soot-stained to signify that she is dying. Also to show a good amount of skin.
Very stylized production.