Did I say prequel? It's an epilogue.
Episode 317: "The Ember Island Players" has aired (the funniest episode of Avatar).
Tomorrow:
Episode 318: The Phoenix King
Episode 319: The Old Masters
Episode 320: Into The Inferno
Episode 321: Avatar Aang
In a more detailed explanation of the trailer, Aang is talking to Momo (???) and he says to him that he has to kill Fire Lord Ozai. Everyone gathers together, all of their friends. It is the hardest battle they are ever going to face and they are all going to help.
The comet has arrived and the Firebenders are using its awesome strength. Everyone is trying to defeat the Fire Nation. It appears also that Aang has re-opened the Seventh Chakra and is able to enter the Avatar State.
Kimi wa ne tashika ni ano toki watashi no soba ni ita
Itsudatte itsudatte itsudatte
Sugu yoko de waratteita
Nakushitemo torimodosu kimi wo
I will never leave you
