Aang has decided to fight the Fire-lord after Sozin's Comet passes. Zuko derails this plan by revealing that Ozai intends to raze the entire Earth-Kingdom continent while under its influence. The gang begins a frantic training regimen while Aang struggles with his responsibilities: his friends exhort him to simply kill Ozai, but Aang clings to the pacifist beliefs of his Air-Nomad heritage. In his sleep, Aang is drawn towards a mysterious island that appears suddenly in the sea; the next day, his friends find June the Bounty Hunter to attempt to locate him again. Ozai bequeaths his throne to Azula and declares himself "Phoenix King", ruler of the known world while Aang awakens on the unknown island now in the middle of the sea.
- Abdicate the Throne: Ozai hands Azula the title of Fire Lord... so he can adopt the even greater self-created title of Phoenix King.
- Avengers, Assemble!: After Aang is reminded he is not alone, Sokka announces "Team Avatar is back!". Cue a shot of each member and their respective element/weapon called out.
- Back for the Finale: June.
- Beach Episode: Subverted. Sokka throws a beach party that Zuko quickly breaks apart.
- Break the Haughty: The first time we see Azula's authority overruled comes when Ozai coldly informs her that she will not take part in the assault on the Earth Kingdom, and will instead remain at the palace. Azula completely loses her composure and objects to his decision, to which he sharply shuts her down. Even though he promotes her to Fire Lord in his stead (A title that will be rendered meaningless anyway), Azula sounds absolutely hurt by his words, feeling like it's exactly how he's treated Zuko. It's this exchange that marks the end of her cold and calculated persona, and things quickly get worse for her from there.
- Bullet Time: When Zuko's fire tunnel catches up to Aang.
- Call-Back: Actress!Aang and Actor!Toph return from the previous episode, much to Katara and Suki's annoyance.
- Calling the Old Man Out: In a way with Azula when Ozai refuses to allow her to come along with him on his conquest, thinking he's treating her like Zuko. The irony is that's exactly what's happening.
- The Coconut Effect: The violence of Sokka chopping the melon is particularly meaningful for the audience, as violence against melons is very often used in media as a sound effect for brutal acts of violence against humans.
- Continuity Nod: As the Gaang enter the seedy bar to find June, the dance party music from "The Headband" can be heard playing.
- Drill Sergeant Nasty: Zuko goes back to being a stern instructor, even when Aang would rather goof off.
- Evil Laugh: Toph gives one while pretending to be Melon Lord."I AM NOT TOPH! I AM MELON LORD!! MUHAHAHAHAHAHAHA!!"
- Final Solution: Ozai's plan for the Earth Kingdom.
- Foreshadowing: When commanded to firebend, Aang bends from his hands and mouth. Ozai will do the same thing in Part 3.
- Funny Background Event: The following dialogue is said while Sokka gets himself out of Appa's mouth. (He put himself in.)Zuko: Why are you all looking at me?Katara: Well you are the expert at finding Aang.
- Gory Discretion Shot: When Sokka "kills" the Melon Lord offscreen, to emphasize Aang's horror at the idea of killing someone.
- Group Hug: The Gaang gathers in a group hug that Zuko joins reluctantly before they are all tackled by Appa.
- History Repeats: As we see in the flashback, Zuko found himself in the same scenario he was in about 3 years ago; at a war meeting with his father and generals, except this time he was needed first and foremost. Zuko hears of a horrible plan he wanted to speak out against, but remembered how badly that went last time.
- Ozai's plan to burn the Earth Kingdom to the ground with the power of Sozin's Comet directly draws inspiration from the genocide of the Air Nomads under Fire Lord Sozin a century earlier.
- Hoist by His Own Petard: Ozai clearly hadn't forgotten what Zuko told him about Azula's failure to kill Aang, or about the fact that she lied to him about this as evidenced by his refusal to let her take part in the assault on the Earth Kingdom that she suggested in the first place; Even more so by his intent to relegate her to a title in which she would no longer wield any true power.
- Jerkass Ball: When faced with the possibility of having to kill the Fire Lord, Aang becomes incredibly hostile towards everyone else.
- Jerkass Has a Point: Azula may be cruel, cunning and even psychopathic. But when Ozai tells her he's not bringing her along to the Earth Kingdom genocide, she calls him out on treating her (his loyal daughter) as unceremoniously as he would treat Zuko.
- Kick the Dog: A case where Ozai passes it off as a Pet the Dog moment. Azula, who has been nothing but loyal to Ozai is finally rewarded for it by being appointed Fire Lord...just as Ozai proceeds to make that title useless and redundant by crowning himself Phoenix King, supreme ruler of the world. Arguably, the title degradation had nothing to do with it; but rather the fact that despite all of her hard work and sacrifice, Azula was not loved by her father and just as easily thrown out as Zuko was the real slight.
- Kicked Upstairs: Azula of all people is hit with this trope upon her father's coronation as Phoenix King; he rewards her with the position of Fire Lord in his stead, a position long coveted by her ever since Zuko's banishment, but her title now means squat in the face of Ozai's new regime.
- Lampshade Hanging: Toph chooses to go with Zuko to find Aang. Her reason:"Everyone else went on a life-changing field trip with Zuko. Now it's my turn."
- Large Ham: Toph as "Melon Lord".
- Mood Whiplash: When Katara finds the baby picture, it's treated as a sweet and funny moment, thinking it's a picture of Zuko. Then Zuko tells them the sweet, innocent child in that portrait is actually his father. Katara immediately rolls it back up and nobody is laughing after this.
- Never Say "Die": Given that this show usually doesn't shy away from it, hearing everyone say "taking [Ozai's] life" rather than saying "kill" is somewhat jarring.
- Not So Different: As soon as Ozai denies Azula her right to take part in the attack on the Earth Kingdom that she had earlier suggested to begin with, she completely loses it and accuses him of treating her exactly like Zuko.
- Ominous Latin Chanting: When the mysterious island is present.
- Omniscient Morality License: Sokka tells Aang that he has this with regards to killing Ozai.
- O.O.C. Is Serious Business: Azula completely loses all of her cold composure when Ozai informs her that she is not to take part in the destruction of the Earth Kingdom, just days after her betrayal by both Ty Lee and Mai. Azula sounds absolutely hurt when protesting his decision, to the point where you can hear her voice breaking as she demands he reconsider. And that's only the beginning of what befalls her after all efforts to impress her father have apparently failed.
- What's more, when Azula angrily reasons he should take her along, Ozai essentially tells her to shut up, and she does just that. Ozai is no one to trifle with if he can silence his relatively talkative daughter into submission.
- Orifice Invasion: Sokka crawling into Appa's mouth because he thinks that Appa ate Momo."Get out of the bison's mouth, Sokka."
- Poor Communication Kills: The Gaang never bothered to tell Zuko they planned to wait until after the Comet to move on Ozai. Zuko made the assumption the Gaang had a plan to deal with his father during the Comet instead of mentioning the genocide plan the guy had in mind, not knowing the group was intending to wait for it to pass.
- Reality Ensues: After an entire show's worth of building up the importance of training Aang before the Sozin's Comet deadline, the Gaang's initial plan of letting it pass is rather pragmatic. Aang simply isn't ready, and since the Fire Nation has pretty much taken over the whole world at that point the deadline is meaningless. Too bad the Fire Nation's new genocide plan forces the Gaang back into action.
- Another goes out to the Fire Nation, who are forced to resort to burning down the Earth Kingdom when they learn that in spite of Ba Sing Se's capture, the Earthbenders remain a serious threat and have forced the Fire Nation on the defensive in the lands they occupied. One of Ozai's generals admits that their army simply is not enough to maintain control of the sheer enormity of the Earth Kingdom continent, and insists on sending the domestic army there before they decide on the Comet instead.
- Aang's internal conflict is this. He knew that he would have to face the Fire Lord; but it never really occurred to him that he might have to resort to taking the man's life; something that not only goes against everything he believed in as an Air Nomad; but as a young boy who shouldn't have to shoulder the burden of taking another man's life, despotic as Ozai is. The severity of the conflict has finally hit home for Aang and he really does not want to kill.
- Finally there is Azula's relationship with her father, who treats her no better than Zuko after having learned she had defied him by attempting to credit Zuko with the Avatar's death, despite knowing full well that he was still alive. He is quick to eject her from the imminent assault upon the Earth Kingdom, and Azula completely falls apart as she realizes that she is just another asset to his global conquest and seen as unworthy of his affection or trust. Devastated, she tries to object and is coldly silenced for it. Ozai tries to make her now-worthless promotion to Fire Lord sound like a reward to appease her, but the damage has already been done.
- The Reveal: Zuko reveals what occurred during the war meeting he attended during "Nightmares and Daydreams" that prompted his HeelFace Turn. Ozai decided to use Sozin's Comet to burn the entire Earth Kingdom to the ground.
- Rock Bottom: The Gaang assumes they've reached this when the Fire Nation took Ba Sing Se. Zuko informs them that they're dead wrong. No matter who won or lost Ba Sing Se in Book 2, the endgame for the war remains the same.
- Sarcasm-Blind:Aang: Maybe we could make some big pots of glue, and then I could use gluebending to stick his arms and legs together so he can't bend anymore!
Zuko: Yeah! And then you can show him his baby pictures and all those happy memories will make him good again!
Aang: Do you really think that would work?
- Shout-Out: The above-mentioned conversation between Aang and Zuko may possibly be one to Xiaolin Showdown, another cartoon with elemental warriors as its focus. When brainstorming plans to defeat the Big Bad of the season, who has actually already taken effective control of the world, someone suggests dumping a bucket of glue on her.
- Skewed Priorities: After Zuko attacks Aang to get him to train, Sokka gives us this:Katara: What happened?
Sokka: Zuko's gone crazy! I made a sand sculpture of Suki and he destroyed it! [beat] Oh, and he's attacking Aang.
- Teach Him Anger: Zuko repeatedly attacks Aang to try to force him into retaliating aggressively instead of running away as usual.
- Terrible Artist: Only with sand sculptures instead of drawings. While Aang can make a pretty decent Appa, and Toph can make an amazing miniature Ba Sing Se (complete with miniature Earth King and Basco), Sokka's attempt at sculpting Suki ends up looking more like a weird anemone than a human face. Suki still thinks it's sweet, though.
- Thou Shalt Not Kill: The reason Aang has such trouble with the idea of killing Ozai.
- Used to Be a Sweet Kid: When Katara found the picture of a toddler playing on the beach while hiding out in Zuko's old summer home, Suki, Toph, Katara and Sokka assume that this boy is Zuko and tease him about this. But much to their dismay, Zuko corrects them, stating that the kid in this picture is actually Ozai, leaving them confused and horrified as to how this sweet and innocent-looking child would one day become the tyrannical monster and unhinged brute they're now up against.Zuko: That sweet little kid grew up to be a monster, and the worst father in the history of fathers.
- "Well Done, Daughter!" Gal: Turns out Azula's no better than Zuko when it comes to daddy's approval. The minute it looks like he's not giving her the respect she wants, she wigs out. It takes some flattery and smooth words from Ozai to calm her down.Azula: You can't do this! You can't treat me like Zuko!
- Wham Episode: Aang learns about Fire Lord Ozai's plans to destroy the Earth Kingdom. Aang also disappears and finds himself on a mysterious island.
- What the Hell, Hero?: Katara scolds Zuko for trying to hurt Aang, but Zuko gives her and the others one of these for lazing about when the Comet was to arrive.
- Worst. Whatever. Ever!: Toph calls her time with Zuko "the worst field trip ever". Zuko calls Ozai the worst father ever.