How does a pacifist protagonist win the war against an evil Empire? It's a surprisingly deep ethical dilemma that Aang wrestles with throughout Book 3, and which comes to a head in the majestic, awesome series finale, 'Sozin's Comet Part 4.' The final battle between Aang and Fire Lord Ozai is the stuff of blockbuster-level dreams, spanning nearly the entire half-hour as the two foes breathe fire and level mountains.

Though it offered no tidy ending, the episode would foreshadow later alliances and establish Azula as one of the most compelling female villains on TV. Tensions fly, unlikely friendships are formed with former enemies, and the episode ends with a thrilling stand-off between the Gaang and Azula, with Iroh and Zuko by their side. Right off the bat, 'The Chase' establishes the rifts among our new core characters (always essential in a tightknit ensemble), and drives a wedge into them with its premise: the group is being inexplicably chased by a relentless machine that won't allow them a good night's sleep. 'The Chase' follows the Gaang after recently welcoming their newest member, Toph, to the group.

Though technically introduced to the Gaang in 'Return to Omashu,' 'The Chase' is where Azula and her team become a force to be reckoned with. Heroic tales are only as good as their villains, and the greatest villain of Avatar: The Last Airbender gets a hell of an introduction in 'The Chase.' I'm speaking of course, of Azula, the Fire Nation princess and resident sociopath whose ruthless maneuverings and chilling charisma help her surpass even the show's ultimate Big Bad, Fire Lord Ozai.

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