- This article is about the mecha suit. For the episode, see "Day of the Colossus".
|"That spirit weapon of hers is attached to a giant mecha suit. It's over twenty-five stories tall!"|
|— Korra describing the Colossus to others in Republic City.|
The Colossus was a skyscraper-sized version of a platinum mecha suit built to carry a giant gun which fired energy blasts powered by spirit vine batteries. It was General Kuvira's secret weapon in the Earth Empire's invasion of the United Republic of Nations. The Colossus was destroyed after Avatar Korra and her companions counterattacked and sabotaged the Colossus to the point of its complete malfunction.
The Colossus was made possible due to Hiroshi Sato's invention of platinum mecha tanks in 170 AG, which were manufactured for the Equalists to use against Republic City's benders in the Anti-bending Revolution. The mecha tank quickly caught on as a method of warfare, being used in the Water Tribe Civil War a few months later. During the anarchy in the Earth Kingdom, Iknik Blackstone Varrick served as corporal and technology specialist under General Kuvira when she sought to stabilize and reunite the nation. The army embraced cutting-edge technology, and Varrick engineered the mecha suit, a more sleek and humanoid version of the mecha tank. Kuvira's army made extensive use of mecha suits, and continued to do so after they proclaimed themselves as the Earth Empire. Kuvira also ordered Varrick to research the spirit vines to use them for energy, and while Varrick defected from her army, the spirit energy cannon was developed.
After Kuvira conquered Zaofu, she ordered that the protective platinum domes of the city be torn down. Her army secretly began the construction of the Colossus as her secret weapon, with her second-in-command and fiancé Baatar Jr. developing its design. Varrick and Bolin informed President Raiko and the United Republic government about the spirit vine technology, and Avatar Korra also discovered the weapon through meditation. Kuvira knew that the construction of the spirit energy cannon had leaked when the Beifong family saw it in action at an Earth Empire factory. However, her opponents were unaware that she was building the Colossus to transport the weapon, and the United Republic assumed she would be transporting it by rail.
The Colossus allowed Kuvira to invade the United Republic weeks ahead of schedule, and she used the spirit energy cannon to eliminate a watchtower on the outskirts of United Republic territory. The existence of the Colossus was discovered by Avatar Korra, Mako, Bolin, and Asami Sato when they scouted ahead on a flying bison. Kuvira fired at the Avatar's team, but they were able to make it back to the city and inform the defense force about the Colossus.
The Colossus made its way to the outskirts of Republic City, standing with the other Earth Empire forces opposing the United Forces on the battlefield, the latter of whom were shocked to see the invention. After President Raiko ordered Kuvira to show down, she used the Colossus's spirit energy cannon to destroy warships in Yue Bay before aiming it at the army assembled at the feet of the Colossus. She gave the president three seconds to respond before she would fire, and Raiko agreed to surrender the city. However, Korra and her allies assembled an Air Nation team to kidnap Baatar Jr. before he could negotiate the president's surrender on Air Temple Island. Baatar was able to radio Kuvira while he was kidnapped, and asked her to stand down, not wanting to be separated from her for the rest of their lives. Although Kuvira pretended to agree with Baatar Jr., she had her soldiers trace Baatar Jr. and Korra's team to a warehouse, and used the Colossus's spirit energy cannon to destroy the building, before focusing her attention on destroying the rest of Republic City.
Korra's team survived the attack with relatively light injuries after Bolin earthbent a heavy wall to protect them from the collapsing building. The group coordinated a plan to take down the Colossus and put an end to the invasion, escorting the hummingbird mecha suit engineers to Future Industries, while the others tried to directly attack the mecha using bending. The airbenders of the Air Nation began to fly around the Colossus to distract it, being swatted at by the mecha's arms, as Meelo and the others used paint to target the crosshairs and windows of the control room, obstructing the view from within. While Kuvira used water jets to clear the obstruction, Bolin used lavabending to create a molten area beneath one of the Colossus's feet. Korra and the Air Nation seized the moment to try to topple the Colossus by using a combined airbending attack, but Kuvira was able to regain balance and fired her spirit cannon, injuring many airbenders and forcing Team Avatar and their allies to a temporary retreat. Meanwhile, an electromagnetic pulse set off by Varrick and Zhu Li at Future Industries Tower managed to disable the platoon of smaller mecha tanks, but had no effect on the Colossus itself, as it was powered by spirit vine energy rather than standard electricity.
The cockpit operators of the Colossus managed to track the electromagnetic pulse to the Future Industries Tower, but Korra and her close allies assembled in the streets as the Air Nation alerted her of the approach of the Colossus. Kuvira fired a beam at Korra, but she avoided it in midair and assaulted the Colossus with earthbending. As Kuvira tried to fire again, the airbenders pushed its barrel downward, directing the beam into the street below. The blast threw the Colossus off balance, and it began to lean against a building. Airbenders began to swarm around the mecha, and Meelo slammed against the building; after missing an attempt to squash the airbender, the Colossus ended up hitting itself. Kuvira fired on Meelo as he flew away, and while he missed the beam, it threatened to hit Jinora, and Tenzin saved her from a direct attack, but both were left unconscious. Bolin, Lin Beifong, and Suyin Beifong attempted to pin the Colossus down by slicing a building and throwing it against the mecha, but it regained balance.
As the airbender and earthbender forces tried to slow the Colossus down, Asami, Hiroshi, Varrick, and Zhu Li arrived, piloting hummingbird mecha suits. The flying mecha were easily able to avoid the spirit energy beams, although Varrick and Zhu Li were nearly crushed after assuming that the Colossus would not be able to reach its own back. Korra managed to immobilize the cannon for a short time by raising up the river with waterbending and freezing it around the right hand of the Colossus, giving Asami and Hiroshi time to approach. Hiroshi and Asami's mecha started to cut a hole into the Colossus using a plasma saw, while Kuvira ordered the cockpit operators to divert more power to free the machine from the ice. After the arm of the Colossus became fully operational once more, Asami was ejected from her mecha, with Hiroshi giving his life to complete cutting an opening into the machine while he was crushed to death. At once, Korra, Mako, Bolin, Lin, and Suyin dashed to the hole and infiltrated the mecha after Korra blocked the arm of the Colossus with a huge block of ice as they dashed toward the breach.
The Colossus eventually managed to fully free itself from Korra's ice and regain balance in the streets of Republic City, while an alarm in the cockpit notified the mecha pilots that the hull had been breached. Mako and Bolin managed to infiltrate the engine room and confront the soldiers stationed there, with Mako noticing the small explosion caused by his firebending blast reaching the huge cluster of spirit vines. As the internal parts of the machine were vulnerable to metalbending, Suyin managed to destroy the reloading mechanism of the arm as Lin battled a soldier, with the master metalbender sisters going on to do as much internal damage as they could. In the cockpit, Kuvira found the firing arm completely unresponsive, and used the mecha's good arm to toss the cannon away, with the weapon falling into the Spirit Wilds of Republic City; Lin and Suyin were kept safe by metal restraints, but were knocked unconscious.
Korra managed to make her way to the cockpit, and started duelling Kuvira, with both opponents dueling each other with ferocity. Meanwhile, all soldiers in the engine room were defeated by Mako and Bolin, but they could not shut down the power. With no other option, Mako decided to destroy the machine by firing lightning at the unstable spirit vines, and the surrounding room began to detonate; the unstable vines left Mako's arm scarred from the attack, and he fell unconscious, with Bolin taking his brother away to safety. As Korra and Kuvira both launched skilful bending attacks at one another, they were thrown off balance by the destruction of the engine room, with beams of energy shooting outward from the Colossus as the machine's core died, and the mecha as a whole was finally destroyed.
However, Kuvira managed to find the spirit energy cannon of the Colossus in the Spirit Wilds, and attempted to fire the machine at Korra. After realizing just how unstable the cannon was, Kuvira tried to shut down the cannon, but could not do so. The cannon sent a beam directly heading toward Kuvira, but Korra stepped in her way and entered the Avatar State to divert the beam with energybending, with the clash of energy causing an explosion of such magnitude that it created a new portal to the Spirit World. Kuvira was tried for using spirit energy as a weapon of mass destruction some months later along with other crimes, though was sentenced to house arrest in Zaofu due to her role in ending Commander Guan's attempt to revive the Earth Empire. Meanwhile, the Republic City Police established an elite squad of metalbenders to deal with mecha incidents in light of the new threat of mecha in the modern age.
The Colossus was a massive mecha suit, as tall as a twenty-five story building. It housed a team of soldiers to defend the machine, as well as pilots to operate the cockpit and control power in the engine room. The Colossus's primary weapon was a large cannon affixed to the mecha suit's right arm, which was capable of firing concentrated energy beams powered by spirit vine batteries mechanically loaded into the gun. The exterior of the Colossus was made of refined platinum that left it impervious to the attacks of enemy metalbenders, though the metal within the interior was bendable. Control of the Colossus's movements was handled entirely by Kuvira, who, while standing atop a gyroscopically-aligned platform, used her metalbending to manipulate the various trackballs and levers around her, which then moved the giant in turn; the controls could also be set in such a way that the Colossus could perform pre-programmed movements automatically without the need for Kuvira's input. The Colossus had an acute sense of balance, and could withstand the strong winds of combined airbending attacks, as well as earthbending material as large as buildings. The Colossus's cockpit also had several unique functions and features, such as the head being able to swivel about, and water nozzles lined across the windows that could clear any obstructions on the glass; in addition, the design of the cockpit's frontal window acted as a crosshair for Kuvira when aiming the mecha suit's cannon. Unlike normal mecha suits, the Colossus was completely powered by spirit vines instead of normal electricity, and a huge ball of spirit vines was gathered in the engine room to power the machine. While this protected the Colossus from an electromagnetic pulse, the nascent use spirit vine energy was inherently unstable to a degree.
- The concept of the Colossus was originally conceived for the finale of Book One: Air, where Hiroshi Sato would have attacked Republic City with a giant mecha suit stationed in Yue Bay, though the idea ended up being used for the finale of Book Four: Balance.
- The design of the Colossus was inspired by the robots from Max Fleischer's Superman cartoons, the Laputa robots from Hayao Miyazaki's Castle in the Sky, and Brad Bird's Iron Giant.
- The liquid metal orbs inside the Colossus were from Suyin's collection of meteorites.
- The initial Google SketchUp model of the Colossus that was used for blocking in storyboards was a kitbash of several real-life and fictional armored or mechanical entities, such as a Volkswagen car, Marvel's Iron Man, Master Chief from Halo, and Samus Aran from Metroid.