As Korra and her friends are being blasted into the air, Kuvira and Lin use their zip-lines to catch the water benders. Hanging against the outer walls of the castle, the four barely cling to their lives as the twins watch over the cliff and shoot ice shards from their hands. Carrying their respective partners, Lin and Kuvira run opposite sides against the outer walls, dodging their attacks. Ice begins to rain towards them as they rush further and further into safety.
"Leave me and Lin with these two. Go find Asami!" Kuvira exclaimed.
"You guys can't fight her alone. Let me help!" Korra demanded.
"They're just buying time. If you don't leave now, Asami might be dead! Now go!" Kuvira responded.
Korra was hesitant to leave at first, but after making eye contact with Kuvira, a sense of trust and faith built between the two allies. The former enemy has now become her friend as the Avatar didn't have the words to express her thanks. Making the tough decision, Korra drops down alongside Kya. Using her airbending skills, she reduced the speed of which she dropped herself landing gracefully with Kya by her side. Seeing the Avatar escaping, Eska dives out the throne room, heading straight for Korra. Eska refuses to fight Kuvira and Lin once more, focusing all her attention on the Avatar.
However, Kuvira manages to incapacitate her during the fall. The metal tears from her armor, flying towards Eska's direction and into Eska's shoulder, locking her in place. Eska screams in agony as Kuvira finally lands an attack on her. It was clear that Eska couldn't ignore the metal benders. Ripping the steel off her shoulder, Eska chases after Kuvira.
From the peak of the palace, Desna notices his sister's in trouble and tries to jump off and save her. However, just as Desna attempts his jump, Lin notices the prince's desire to assist and intercepts him. Grappling herself towards the highest peak of the castle, Lin reels in the metal wires and tackles Desna back into the room. As she does this, Desna kicks Lin off him, forcing her back towards the edge of the cliff. Lin almost falls off into her impending doom but manages to catch herself just in time.
Inside the throne room, no walls surround the two fighters with the strong winds pushing against their bodies. Lin was reconsidering her revenge, not expecting Desna and Eska to be their mysterious villains. Just as puts on his Owl mask, Lin asks him a question.
"Why are you doing this? I can see why Eska, but I can't seem to understand your intent." Lin inquired.
"I never wanted Eska to turn out like this. I even tried to reason with her but she won't listen. As much as I really want to help you, detective, I can't go against my sister. Bolin maybe her turtle dove, but she means everything to me." Desna replied.
"There's still time! You can explain things to her more clearly!" Lin stated.
"Have you seen her face? The reasoning isn't going to cut it... All she cares about is blood being spilled. Everyone that gets in her way wants her dead and I can't let that happen." Desna stated.
The arena was quiet with only the sound of the arctic wind howling against their ears. Snowfall filled the room as the two opponents stared directly at each other. Slowly picking up the snow from the ground, Desna created a sword using his water bending. With enough said, Lin rushed towards Eska as she jumped high in the air and swung her blade towards Desna's neck. Desna manages to parry the attack, lunging his sword towards her chest. Evading the attack, Lin backed off as fast as possible with Desna whiffing his attack.
With the limited space, close-quarter combat was the only solution. The two jumped towards each other as they continued fighting.
Meanwhile, Kuvira and Eska were fighting on the outskirts of the central caste. Gliding against the walls, Eska chases after Kuvira, throwing ice projectiles against her. Kuvira knows that once she gets hit by those objects, her whole body would freeze causing more trouble for the young Avatar. Kuvira was going to beat her opponent by using the object that Varrick gave her before leaving Republic City. Remembering she left the tool at the throne room, Kuvira had to find her way back.
Zipping around the castle walls, Kuvira continued to distract Eska, using the castle itself as a shield to intercept her attacks. Kuvira tried returning the favor as she would tear a piece of her armor and throw it towards Eska. Even though Kuvira's attacks were perfectly accurate, they didn't amount to much.
Every throw would instantly freeze, turning it brittle and weak. The metal would corrode instantly and would later turn into dust, breaking before hitting Eska.
Kuvira didn't care if it hit her or not as she just wanted to use herself as bait to give Korra enough time to find Asami. She frantically dodges the shards when suddenly, an idea comes into her head. As a window is about to approach her, Kuvira bends an enormous piece of the castle behind her, using it as a barrier between Eska and herself. Tired of Kuvira running around like a scared mouse, Eska forces her way through the wall. She is blinded by the debris for a few seconds, giving Kuvira just enough time to hop through the window she was headed for and earth bend it shut.
With this, Kuvira made it appear as if there was never a window, to begin with, evading Eska's wrath. With the little time Kuvira bought herself, she started zip-lining through the stairs. While it did buy Kuvira some time, her plan wasn't enough to fool Eska.
Eska takes a deeper look at her castle walls and notices a part of the castle with a different color compared to the rest. Realizing it was the window Kuvira had covered, Eska pressed her hand against the building, creating a hole in front of her. Eska screams in rage as Kuvira refuses to fight her fairly and bolts into the castle. This distraction gave Kuvira a three-story head start, rushing towards the peak.
While Eska could have just zoomed towards the top and intercepted Kuvira, her eagerness to kill the one-armed fighter prevented her from noticing Kuvira's intent. At the top of the castle, Lin and Desna continue to fight, parrying each other's attacks. For every swing Lin makes with her legs, Desna blocks them using his sword. After numerous amounts of trading attacks, Lin lifts her leg high in the air, swinging her blade down against Desna. While he tries blocking the attack with his sword, perpendicular to Lin's attack, Lin's blades were too dense for Desna's blades to intervene. With her steel meeting his ice, Desna's sword shatters into a million pieces as Lin's legs penetrate his shoulder.
Stuck against his shoulder, Lin turns her blade cross, making a V-shape carving in his chest. Only his right shoulder and neck remain attached to his head. Blood drenched Lin's body as Desna's lifeless half pours blood like a fountain. Lin stood still, finally killing the Owl as she celebrated her victory by showering in her enemy's blood. The celebration came to a halt as Lin started hearing crashing debris coming from the stairs. An eerie feeling jittered through her skin as she assumed Kuvira was dead and Eska was coming for her next. Completely exhausted and out of gas for her zip-line, she closed her eyes in hopes of a quick death.
"Hand me the briefcase!" Kuvira yelled.
Entering the room, Lin opened her eyes, relieved to see Kuvira was safe. Turning behind her, she noticed the briefcase her niece had brought and rushed towards it. Opening the container, a mist slowly flows out, exposing a hexagonal object. Lin wasn't sure what it was but didn't question the technology as she handed it to Kuvira. Sliding against the icy floor, Kuvira began pulling a cable from her metallic arm, attaching the hexagonal sphere to it.
"What the hell is this?" Lin asked.
"It's an engine," Kuvira replied.
"For what?" Lin continued.
"You asked me what the barrel in my palm is for right? Well, it's about time I showed you!" Kuvira stated.
With the engine attached to her arm and the power source inside, Kuvira's metallic arm starts glowing bright purple, just like the robotic cannon she used to take over Republic City. With the engine revving and the arm glowing brighter and brighter every second, Desna started getting sinister vibes about Kuvira's new invention. Sensing his sister boosting herself through the stairs, Desna screams her name, trying to stop her from coming up.
"Eska! Run!" Desna screamed.
Arriving at the top of the castle, Eska couldn't slow her momentum as she ignored his warning. With the nine-tailed fox and metal bender finally face to face, Eska's eyes open as she's directly within the barrel's path. Although Eska tried running from the glow, it was too late. Kuvira shot an extreme burst of spiritual energy with the cannon at maximum charge, disintegrating through everything within its path. Ice turned into vapor and bricks turned into the air as Eska's body burned to a cinder. Within ten seconds, the laser died down along with Eska's brain function.
Just below Eska's breasts, a gaping hole is revealed within her chest. With no heart, lungs, or ribs, Eska falls into her immediate death. Fully regenerated, Desna rushes over to his sister, holding her head between his hands. With a desperate gleam in his eyes, Desna tries performing CPR, blowing into her lifeless mouth. It was obvious that Eska was dead, but Desna's stubbornness didn't accept the current reality.
Even though the cult was responsible for Suyin's and Opal's death, guilt emanated within her soul. With pain coursing through her chest, Lin remembered her sister's death. Staring down at Desna, all she could do was compare how his emotions were similar to what she felt when Suyin died. Feeling bad for the brother, Lin tries to talk to him, even though she doesn't have a single clue on what to say.
"I... I'm sorry it had to come to this." Lin stated.
"Help me! She's dying!" Desna exclaimed.
"She's already dead!" Lin pointed out.
"She can't be! She's my sister. She's the princess of the Northern Tribe! She can't be..." Desna stated.
Desna wanted to deny his sister's death as much as possible, but even faith couldn't bring back the dead. Suddenly, the ground started to shake, indicating the building was collapsing upon itself. Lin grabs a hold of Desna who was still carrying Eska's corpse as Kuvira grabbed everyone away from the scene. As the beautiful crystal palace turns into dust, the burst of energy from the collapsing building, and the weight of four people, send them flying away causing Kuvira to lose traction of their hooks. Luckily, the four fighters weren't so far off the surface and only suffered minor injuries as they pummeled into the ground.
Dust fills the entire kingdom as everyone around the wreckage can't see anything within a ten-meter radius. Lin and Kuvira are right next to each other but manage to lose Desna and Eska. With the people running away from the crash in panic, Kuvira and Lin were the only people around. Comforted that the two are alive, they begin wandering through the smog in search of Desna.
With an hour passing, the two Beifongs' search would be over as the smog cleared and they were able to see Desna cuddling Eska in the distance. They slowly walk towards the two siblings. Tears drop from his eyes as he finally admits her death.
It didn't cross his mind what life would be like without his sister. During the hour Lin and Kuvira looked for him, he began pondering if there was any hope for him. After much consideration, Desna didn't couldn't see any positives through his grief. Looking at the two metal benders, he asked to be executed.
Kuvira and Lin stare at him with a gloomy look on their faces. While they finally got their revenge, all they could feel was sorrow.
"I've never known what life would be like without Eska. It feels painful yet empty at the same time. Is this what it felt like when my sister killed your Opal?" Desna stated.
"Yes... How does it feel?" Kuvira asked.
"It's painful... I couldn't believe this is what we were doing to people like Korra. To you two especially. Perhaps it was the same reason Eska wanted to kill her. Perhaps she sought some solace and tranquility if she killed the two of you." Desna replied.
"I don't care what you feel, you're coming with..."
Kuvira was interrupted as Lin tried having a heartfelt moment with the prince. Sitting down beside him, she begins sharing her story.
"When I killed two of your allies. I didn't feel anything. I wasn't happy nor relieved that they're finally gone. I just felt bloodthirsty. I thought killing you two might be enough, but after looking at you holding your sister, I realized it wasn't." Lin stated.
"Are we both the same coin on different sides? Are we both different people with the same problems?" Desna asked.
"Most likely." Lin stated.
"This cycle of revenge has to end. I can only foresee a future where our offspring make the same mistakes we do.... Please do me a favor.... kill me." Desna stated.
Kuvira gets furious as the masked villain asks for a pleasant death. Putting her arm in front of her, Lin silences her vengeful niece.
"What about your next air?" Lin asked.
Lin was tired of killing her enemies and tried to convince Desna to choose life over death.
"The people get to decide who their leader is, not me..." Desna replied.
"Don't you want to get married? Have kids at least?" Lin asked.
"I asked the same thing with Eska when we were little. We would spend all our time pondering about that. She replied yes but I don't think she meant as much as I did. A world without her is a world that I don't want to live in. Please kill me here. I want to be reunited with Eska." Desna pleads.
Moving closer towards Desna's head, Lin lifts her leg high in the air as she drops the heel of her blade through his neck. His head starts rolling against the cold, stone floor. His eyes were wide open with his mouth smiling with content.
In Desna's perspective, everything turned white. The noise of fire burning houses and buildings crashing suddenly disappeared. With his lifeless head against the white floor, he sees a happy Eska walking from the distance. His lifeless body smiles as he's finally relieved of having the burden to kill more members of Korra's friends.
Unlike Eska, Desna never wanted to kill anyone and only wanted his sister safe. After being a member of the Iron Bloods alongside his sister, his attempts of convincing Eska it wasn't Korra's fault all turned to naught. With Eska now a member of the Iron Bloods, Desna was forced to kill innocents. While Eska's murders were fueled by rage, Desna's were fueled by the necessity to protect his sister from anyone who tried to harm her.
The consequences of his sister's actions started reflecting towards him. However, his sister's death became a sudden blessing in disguise as his days of murder were finally over. Relieved of this duty to protect his sister, Desna can finally rest in peace, living his spiritual life with his sibling for all eternity...