Enter the Void/Venom of the Red Lotus is the best finale of the LoK, and one of the best pair of episodes in the franchise. Which is fitting, because Book Change has been the only season of Legend of Korra that is punching in AtLA's weight class. While Change has suffered no blunders, it isn't mistake free, and there are even minor miscues in its finale which have been nagging issues all season. Let's talk about those first.
Jinora is no master airbender. She's simply not shown to be one. She has an understated role in the story, and a lot of her personal growth is instead given to a new character. While the end scene has her as the focus, it feels unearned. It's another bit of disappointing circumstance for her character, because she has potential for interesting character dynamics with Tenzin and Korra. While her initiation scene actually works, it's in spite of her (I'll specify why later). Jinora's most recurring contribution to the show is being a person of relative importance for another character to save or mourn over, while her lack of character development and ability leaves much to be desired in the wake of all the meaningful plot she is integral to. The writers of the show have already admitted to not knowing how or why Jinora does what she does, so I suppose they want us to forget all of that and focus on how much she looks like Aang. The new (old) look is snazzy on her, at least.
The other problem element is the general lack of cohesiveness with Team Avatar. They are always cordoned off into doing separate things, and not much of the plot rolls through that group as a whole. Aang and his entourage faced most of the story together, and were stronger characters for it. While each member of the LoK team found something to do in the finale, only Mako and Bolin supported each other in battle. It doesn't make for great group dynamics when so much of who each of these characters are is determined in absence of one another. Which really is another way of saying they're generally boring when together at best, and actively destructive at worst.
Aside from the aforementioned issues - which have been entrenched problems with the series almost since LoK began - the finale was great.
I want to first point out that the choreography and animation of the show has been outstanding all season, but especially here. You really get a feel for these characters most evidently in the flow of battle. For example: in the brothers' runback with Ghazan and Ming Hua, Bolin is more confident in his attacks because he's emboldened by being able to lavabend. And although he's now more of a match for Ghazan, the latter still gets the upper hand due to experience before Mako makes it a 2v1. All of this would have been apparent even if the characters never said a word. Another fine example is how Korra is characterized as a berserk force of nature when she's in the Avatar State, dying from poison. She's jumping around like Ang Lee's HULK and rocketbending like Ozai. It speaks to both Korra's natural disposition and her mental state at the time. A true force of elemental power.
Everything that happened was extremely clear and readable. It let the drama build organically because the characters moved and reacted to things believably. In this sole important avenue does LoK actually hold a slight edge to AtLA. It's a sign of the times in advancement of technique and technology. Beautifully executed animation.
The rest of the finale builds on top of the fine foundation set by the animation. Multiple arcs, both plot and character, reach relatively satisfying conclusions. And most importantly, nothing was contrived and everything makes sense (with respect to the season it is contained). This is an important factor, one lesson Mike and Bryan no doubt have learned from the reaction to Book Air's finale. When the audience spends so much time trying to make sense of what's happening on screen and why, it detracts from the entire production. We know how Zaheer can fly, we know why Korra is limited while in the Avatar State, and we know that is how Zaheer is able to overcome a fully powered Avatar, when otherwise he would have no chance. Best of all, it all occurs due to the agency displayed by the characters themselves. The plot is carried by them, the major characters; not in spite of them. Coincidences such as a random rock outcropping being the deciding factor of the drama does not occur in Change's finale.
One such arc that I don't see mentioned often is Bolin and Mako's mini rivalry with Ming Hua and Ghazan. I understand why it's not really talked about given how it's mostly incidental within the plot, but bits of small characterization can be extracted from their interactions. While Bolin gaining lavabending is an obvious result of this particular plot elements, it also allows the viewer to see some humanizing aspects of the criminals such as Ghazan and Ming Hua's possible courtship and how Ghazan is respectful of his opponents in battle. It's small stuff that goes a bit of a way in making the viewer care for the antagonists. Or at least understand a bit about who the characters are.
It's these little things that help make Change so superior to the other books in the series. Possibilities arise from small directions in writing or animation. Photographs are scrutinized, lines are debated. The writing also smartly veered from the failing romance plotting and refocused around the moralities and tenets of airbending culture. It was the first time in Legend of Korra that the major plot and motivations of the characters honestly complemented each other throughout the season. The rebuilding of a culture was Korra's goal from the beginning of the season, and it is within that culture that her foil and possible downfall is immersed. All the plot is in service or tangential to this paradigm. Because of all this can the main character finally grow.
Korra has constantly been struggling as a character, as a leader, and as the Avatar. And she's at her lowest point yet. Veelk has said much about this already so I won't retread on well defined ground, but the end scene is effective because of her. To be Korra is to be powerful, for better or worse. In that wheel chair, looking on at Jinora's finest moment, she sees both the product of her leadership, and her possible replacement(s). While it's a foregone conclusion that Korra will return to form, this situation she has been put in will be the first time Korra is truly confronted with obsolescence. It will, for a time, strip her of her most identifiable feature and force her to truly understand what the cost of battle can be and what the realities of being a leader are.
LoK Change has been a positive change on multiple fronts, ultimately bringing us to the main character's most fundamental challenge. Perhaps the most valuable thing this season has given me is the belief that the writing can be competent enough to follow through on most of the plot points introduced.