Warning: Full spoilers from the episode to follow.
The Legend of Korra's Book Three finale began on a rather dire note, as Zaheer had chained Korra to the walls of an abandoned cave (the interior of which bore a striking resemblance to the Crystal Catacombs in Avatar: The Last Airbender's "The Crossroads of Destiny.") Worsening Korra's situation was her ingestion of a deadly poison that would test her resolve for the better part of (the appropriately titled) "Venom of the Red Lotus." I was particularly struck by Korra's initial hallucinations of enemies past, including Amon (!), Unalaq and Vaatu. To me, this read as Korra facing her deepest, darkest fear: living in a world where the Avatar was no longer needed. Naturally, Korra had struggled with this fear in the past, but to see it manifest in such a visually potent way was definitely disturbing, if not thought-provoking.
The airbender breakout was another great scene that featured some of the ensemble's best character moments. From the airbenders working together to snatch the keys, to Lin, Su and Asami taking out the guards, it was nice to see some of the other characters contribute, if only a little, to the climax of Book Three.
That said, the most active players here were Mako and Bolin, whose second encounter with Ming-Hua and Ghazan proved even more exciting than the first. At last, Mako hit Ming-Hua with the good stuff (lightning, son!), and Bolin countered Ghazan's lavabending with, well... lavabending! Overall, I think the creators did a good job of writing out both fugitives, while also alluding to their respective deaths.
Of course, the obvious centerpiece of "Venom of the Red Lotus" was Korra's face-off with Zaheer. Acting under the false (but narratively smart) assumption that her father was dead, Korra's drive here was clearly fueled by rage, as evidenced by her now-animalistic appearance. As is now tradition with the finales, Korra was sporting a badass new look: untamed hair, bare feet and shackles wrapped around her limbs. (Cue the fan art!)
Meanwhile, Zaheer remained completely composed, as he and Korra took to the sky. Indeed, their fight almost evoked a superhero-like quality, with Zaheer typifying Superman and Korra being all like, "HULK SMASH!" Even Jeremy Zuckerman's epic score had kind of a comic-book-movie feel to it. That's not to mention Jinora's vortex special, which ultimately brought Zaheer to his knees. In the end, it was a harrowing but exhilarating battle.
Alas, with great battles come great consequences. If we're to presume that Zaheer's poison was some kind of mercury (I suspect it was), it's no wonder that it took such a physical toll on Korra. To see her in such a vulnerable, weakened state, especially weeks later, was truly heartbreaking. Specifically, it was the Asami/Korra scene that really got to me, as it showed just how much Korra's selflessness had cost her. (Also, Korrasami foreverrrr!)
Jinora's tattoo ceremony was another gratifying sequence that revealed several clues about Book Four. First was Tenzin's speech, which hinted at the airbenders reverting back to their nomadic roots and becoming international peacekeepers (Jedi Knights, basically). Second, now that Jinora's an official airbending master, it seems she'll be heading up Tenzin's new initiative, making her a surrogate "Avatar" of sorts, at least until Korra's healed up.
Speaking of which, I also wanted to address that final shot, as I think it spoke volumes about Korra's character. As of right now, it's uncertain what impact her injuries will have on Book Four and how that will play out. She could be back on her feet in a few weeks' time, but it's also possible that she never fully recovers. In any case, I think that final moment was a beautifully executed end to Book Three and a perfect counterbalance to Korra's optimistic speech at the end of Book Two. Now, more than ever, change is on the horizon for the mortal world. With evil spirits (and potentially more Red Lotus members) still looming in the shadows, it's clear that Book Four is heading toward something big.
While The Legend of Korra's Book Two finale may still hold the record for highest stakes, Book Three's "Venom of the Red Lotus" offered a more emotional and poignant season finale, albeit one with just as much action and excitement. The final confrontation between Korra and Zaheer, for example, was gorgeously animated and scored but also very raw and personal. Meanwhile, the Bending Brothers' fight against Ming-Hua and Ghazan brought its own thrills. However, the aftermath of said events was perhaps the most hard-hitting aspect of the finale, as Korra began her road to recovery and Tenzin ushered in a new era for the Air Nation.