Tropes A to H (Chekhov's Gun) | Tropes I to P | Tropes Q to Z (Ship Tease, Shout-Out, Shown Their Work, Wham Episode)
- "Winter Solstice Part 2: Avatar Roku." You aren't just going to learn the four arts because of tradition, Aang. You have to do it in less than eight months, or the Fire Nation will conquer the world.
- "The Library" not only marks the end of the more episodic half of the series, but gives a concrete plan to actually fight back against the Fire Nation, setting the rest of the series into motion.
- "Crossroads of Destiny", the second season finale. Ba Sing Se is taken over along with the rest of the Earth Kingdom, Zuko chooses the Fire Nation over Iroh, and Aang is killed, only being revived thanks to Katara's spirit water. The last words of the season are what really drives the point home.Earth King: "The Earth Kingdom...has fallen..."
- "The Day of Black Sun" parts 1 and 2 - What was built up as the definitive strike against the Fire Nation turns into a colossal failure when it's revealed that the Fire Lord knew about the invasion long in advance, having Azula set up a trap to stall the heroes until the firebenders get their powers back. Notable also for Zuko making a definitive HeelFace Turn and deciding to join the Avatar.
- "The Boiling Rock Part 2": Azula is betrayed by Mai and Ty Lee. Shocked that she could no longer control them through fear, and desperate that she lost the only two people whom she considered her "friends", Azula starts to descend into insanity.
- The first part of the series finale, "Sozin's Comet", reveals that Ozai isn't going to use Sozin's Comet to subjugate the Earth Kingdom- he's going to use it to burn the entire continent to the ground.