Teridax

"Your talents are still of some use to me, and so I will not kill you... today. But one day – perhaps in a year, or 1000 years, or 100,000 years – I may grow tired of you, Icarax. You may cease to be amusing, with your posturing and your boasting and your lust for battle. And on that day, your armor will be a meal for metal-eating scavengers, and your essence a wisp on the wind."

- Teridax to fellow Makuta, Icarax

Teridax (more commonly known as the Makuta and the Makuta of Metru Nui) was a Makuta and the leader of the Brotherhood of Makuta after overthrowing Miserix. He was the main villain in BIONICLE.

Early Days
The being known as Teridax once served the Great Spirit Mata Nui as part of a Brotherhood, whose job was to create and alter creatures as needed; the Brotherhood soon also took on the job of protecting Mata Nui's chosen people, the Matoran. Teridax was put specifically in charge of the city of Metru Nui and its surrounding region by the former leader Miserix. In this time, Mata Nui and Teridax were so close that they were considered brothers.

At one point eighty thousand years ago, the Brotherhood had discovered through the traitor Takadox that a military alliance called the League of Six Kingdoms was plotting no less than the overthrow of Mata Nui himself. The Brotherhood allied with Mata Nui's champions, the Toa, and Teridax led a preemptive strike against the League and their Leaders, Warlords titled "Barraki". The operation was a complete success and all six Barraki were captured, but as Teridax was about to execute them a stranger named Botar appeared and made the Barraki vanish into thin air. Though Teridax would occasionally wonder about the stranger and what he had done with the Barraki, he would more often consider the League's ultimate goal: a Barraki was ultimately unworthy to replace the Great Spirit, but a Makuta...

Perhaps spurred on by this thought, Teridax and the rest of the Brotherhood eventually became corrupted and began oppressing Matoran. soon, Teridax called all Brotherhood Members to Destral and described his plan. Miserex went against this but no Makuta supported him. Teridax claimed leadership of the brotherhood and ordered Miserex executed. The reasons for this are not completely clear; though it is said that the Brotherhood was jealous of the high regard that Mata Nui was given by the Matoran, and it is also possible that the Brotherhood sincerely believed that they could protect the Matoran best by ruling them with an iron fist. In any case, Teridax and the Brotherhood's corruption was not widely known and they were still considered by many to be guardians.

At some point, six Toa were selected to be Teridax's personal bodyguards. He, of course, was more than capable of defending himself, so having bodyguards was purely a matter of prestige. These Toa became known as the Toa Hagah.

The Great Shadow
"Too late Toa, the shadow has arrived."

Eventually, Teridax revealed to the other Makuta a plan to put Mata Nui to sleep, intending to take his place in the minds of the Matoran as their savior. He used the Plan to gain the support of the rest of the Brotherhood, effectively overthrowing the Brotherhood's original leader, Miserix. Teridax then sentenced Miserix to death, although for some reason the execution never took place, and instead Miserix was imprisoned on an island far to the south. Teridax then set his plan into motion. He was probably not aware that doing so could lead to the Great Spirit's death - and with it, the death of the universe - but if he was, perhaps he saw some sort of advantage in the possibility. In any case, Teridax attacked and left Mata Nui to slowly succumb to his injures for three hundred years.

Around the time of Teridax's attack on Mata Nui, the Toa Hagah discovered the Brotherhood's corruption and treachery and rebelled. They struck by surprise, overpowered the Dark Hunters guarding Teridax's stronghold, and stole the Kanohi Avohkii, the Great Mask of Light. At some point during the battle, they confronted Teridax himself, and wounded him significantly. However, during their escape, they were ambushed by Roodaka, one of Teridax's servants, who used her Rhotuka Spinners to mutate them into freakish, Rahkshi-like creatures she called "Rahaga". They managed to escape, however, and safely hid the Mask of Light, so that when it was time for it to be used, the Brotherhood couldn't stop it...

When Mata Nui was about a year and a half from lapsing into unconsciousness, Teridax kidnapped Turaga Dume, the leader of Metru Nui, and, posing as Dume, began sending the Toa that guarded the city to close the sea gates from which they never returned. To aid in this, he hired three Dark Hunters: Nidhiki and Krekka would help inside the city, while the Hunter codenamed "Eliminator" would stay outside and kill the Toa sent out to close the gates. He also brought in a predatory pet bird named Nivawk to act as a spy. Eventually, only Toa Lhikan was left. "Dume" also requested that the city's best maskmaker, Vakama, try to make a Mask of Time that would help in his plans."dume" than created the morbuzak and released it on the outskirts of ta-metru.

After the Morbuzakh plant was unleashed to drive the Matoran to the city's center, Lhikan began to get suspicious and decided it was time to choose Matoran to become new Toa. Teridax tried to subtly influence this decision so that Lhikan would choose Toa who would not be able to stop him; but Mata Nui, knowing the danger, influenced Teridax so the Toa chosen were the ones destined to succeed.

While these new Toa Metru - which included Vakama - were able to destroy the Morbuzakh, Teridax went forward and had the city's Vahki enforcers continue the job that the Morbuzakh had started: kidnapping Matoran and putting them into spheres that would erase their memory, allowing Teridax to "save" them from their imprisonment. By the time the Toa Metru discovered his plot, it was too late and the entire population of Metru Nui had been put into the spheres. Even worse, Mata Nui had finally fallen into a coma, bringing on the Great Cataclysm.

The Toa tried to escape the city with a few spheres, intending to return for the rest, but Teridax gave chase; boosting his power by absorbing Nidhiki, Krekka, and Nivawk into his body (killing them in the process). Vakama went to face him alone and tried to use the Vahi that he had made against him; Teridax was impressed that he was able to make a Vahi and offered him a position with his Brotherhood and as part of his essence, but Vakama refused. Unfortunately, Vakama's inexperience led to both of them getting caught in the mask's slow-motion effect. Teridax had fired an inescapable, deadly blast when Lhikan, now a Turaga, jumped in the way and took the brunt of the blast for Vakama, and he soon died from the wound. Inspired by Lhikan's sacrifice, Vakama began to truly challenge Teridax, and with the help of the other Toa Metru, sealed Teridax in a prison of solid protodermis.

The Thousand Years of Darkness
But even imprisoned, Teridax was not helpless. He telepathically summoned two of the Brotherhood's lieutenants, Sidorak and Roodaka, to bring their Visorak armies to Metru Nui. Once there, Roodaka painfully cut away a small shard of the prison, intending to absorb the Toa's elemental powers and use them to break the seal. However, things did not go as planned and Roodaka was instead attacked with blasts of elemental power, but the effect was the same: the seal was broken and Teridax was free again. The prison shard was claimed by the Toa Metru, who later used it to represent Teridax when telling their tales.

A short time later, Teridax began searching for the Vahi, which fell into the sea during his fight with Vakama. But Vakama was also looking for the mask, as was a mutant named Voporak who searched on behalf of the Dark Hunters. Teridax found Vakama and trapped him in an illusion, hoping to trick Vakama into giving him the Vahi - but Vakama broke free of the illusion, and Teridax was furious to learn that Voporak had taken the mask. He offered Vakama a truce until they got the Vahi back, and he kept his word - until the Dark Hunter leader, the Shadowed One showed up, hunting the Toa that he was sure was responsible for Nidhiki and Krekka's deaths. Teridax started bartering with the Shadowed One over the Vahi, but Vakama cut negotiations short when he pointed out that it was Teridax who had killed Nidhiki and Krekka. Enraged, the two Hunters attacked Teridax, breaching his armor; but Teridax was able to knock Voporak out and make the Shadowed One age prematurely in Voporak's defensive field; because of this incident, the Shadowed One declared war on the Brotherhood of Makuta. In the confusion, Vakama snatched the Vahi and began flying away.

Teridax soon tracked down Vakama and demanded the Vahi, but Vakama threatened to destroy the mask - and with it, the entire space-time continuum. Extremely reluctantly, Teridax agreed to give the now-free Matoran a year of peace and to leave Vakama's allies in Metru Nui alone.

He then returned to Destral and challenged Icarax to make him stop terrorizing Matoran with his Manas interesting enough he let Icarax live for now. He then went to one of his many lairs this one called Mangaia.

In that year, Vakama and the other Toa Metru brought the Matoran to the Island of Mata Nui, became Turaga, and led them in constructing villages. Teridax, meanwhile, located a lost Matoran named Ahkmou and used seductive lies to make him an ally.

Once the year was up, he began to harass the Matoran by creating Kraata and using them to enslave the local Rahi wildlife; forcing them to attack the villages. His aim was hopefully to intimidate the Matoran into surrendering, but more importantly to keep the Matoran away from Metru Nui. But the Matoran fought back, driving off the Rahi and freeing some from Teridax's control. However, Teridax would keep on enslaving more, and the stalemate would continue for nearly a thousand years...

The Coming of the Toa Mata
"You cannot destroy me... for I am nothing."

Finally, a wanderer named Takua was able to find six Toa Stones that were scattered around the island, created and hidden back when the Turaga were the Toa Metru. Bringing these together at the Kini-Nui Temple summoned the Toa Mata to Mata Nui. At first, Teridax tested these beings to make sure they were real Toa; including using Ahkmou's help to spread an epidemic among the Po-Matoran. He even went so far as to fight them directly. Once he was convinced, he retreated and awakened the Bohrok swarms for the Toa to deal with. He held no illusions that the Bohrok would be able to defeat the Toa, but they would keep the heroes busy; and once the swarms failed there was the chance that the elite Bohrok-Kal could be a threat to the Toa.

But the Toa prevailed against the Bohrok threats, transforming into more powerful Toa Nuva in the process. Whatever schemes Teridax was plotting in this time were abandoned a short while later, when Takua found the legendary Avohkii Mask of Light. Legends stated that the mask's wearer, the Toa of Light, would appear in a time of darkness; and Teridax quickly sent out Rahkshi to keep the prophecy from coming true. He also appeared to Takua, warning him that the consequences could be fatal for his friend Jaller if he didn't give Teridax the mask. But these attempts failed, as Takua realized his destiny to become the Toa of Light, renaming himself "Takanuva" - though Teridax's warning rang true, as Jaller did indeed die in the last battle with the Rahkshi.

Shadow versus Light


The next day, Takanuva went to challenge Teridax alone; though once he got there he told his friend Hahli (who had stowed away on his vehicle) to go back and bring all the Matoran. While she was doing this, Teridax challenged Takanuva in the Matoran sport of kolhii, and the ensuing "game" damaged much of the lair. When the Matoran arrived, Teridax took out the lair's last remaining pillar, causing a cave-in and cutting off the Matorans' escape route. Takanuva then tried to rip Teridax's Mask of Shadows off of his face, causing the two to fall into a pool of energized protodermis and emerge as a single being, Takutanuva (see Takutanuva section below). Takutanuva opened the way to Metru Nui, and the Teridax side(being enlightened by the Mask of Light piercing the lies he had told himself over the centuries)even helped bring Jaller back to life,and as a result,when they split apart,Teridax lost an estimated 50,000 years of his life,the average lifespan of a Matoran,although it hardly made any differance, as Teridax's lifespan is at least 500,000 years, but the energy spent on the resurrection made Takutanuva too weak and the gate he was holding fell and crushed him. Takanuva was quickly restored from his mask, but Teridax is believed by the world to be dead.

Despite the apparent victory, Takanuva has some suspicions that Teridax let the Matoran win to further some grander plan. According to series writer Greg Farshtey, "My feeling has always been that Makuta knew that the Toa and Matoran would make it back to Metru Nui eventually -- so he intentionally lost the fight to Takanuva, allowing them to go back there thinking they had won. (Granted, he didn't expect to be crushed by a door, but hey, stuff happens.) This way, they would be occupied with rebuilding for some time and convinced the danger from Makuta was largely over, and thus ignore what he was REALLY up to."

Ignition
Unknown to all, Teridax still clung to life as a mass of energy, though the loss of his physical body severely weakened him. A few weeks later, a gang of thieves calling themselves Piraka heard rumors of Teridax's death and went to investigate. They found his crushed armor and one, Reidak, tried to claim his mask but it hit him with energy pulses until he let go, ending up throwing it into the sea. Seeing them as perfect pawns, Teridax used his telepathy to plant knowledge of the powerful, cursed Ignika Mask of Life in their heads; Teridax hoped to gain control over the Ignika, which would give him control over when and if Mata Nui's life gets saved as well as the ability to take life from enemies beleiving the he could control the Ignika without dying because he was so powerful. He also specifically influenced Zaktan's behavior, as he was the Piraka leader and had some authority over the others.

On Voya Nui, the Piraka constructed a vat centered around a crystal that collected Teridax's substance, in the form of a virus called "antidermis". Only Zaktan knows the antidermis' secret, that it is really a form of Teridax; and he is the only Piraka that can approach the virus collection vat without becoming physically ill. While the vat keeps Teridax's energy collected so that he doesn't dissipate, the Piraka have infected the island's Matoran with small amounts of the antidermis, enslaving them to the Piraka's will. The Piraka's ally, Brutaka, has also found that absorbing some antidermis into his system gives him a temporary boost in strength and agressiveness.

In Brutaka's last fight with his ex-friend Axonn, he tries to get to the antidermis vat so he can become stronger. However, Axonn destroys the vat before he can get there - and as the virus dissipates he swears he hears a second scream besides Brutaka's.

Mahri Nui
"I could just kill you, Matoro, take the mask, and do the job myself, but it's so much more amusing this way."

In Mahri Nui, Teridax took over the body of the Pit Robot Guard Maxilos. In this form, he persuaded Matoro to reanimate Tuyet, attempting to use her to recreate the Nui Stone. But he was stopped by Karzahni who heard him speak of the Staff of Artakha. The two started fighting and Karzahni summoned an army of Manas. Teridax made half of them turn against the other half using his powers of rahi control. Karzahni then got angry and used his powers, showing Teridax the future of the Toa Nuva awakening Mata Nui. However, Teridax recovered. After he damaged Karzahni`s mind and hurled him out of sight, Icarax arrived with the staff and Teridax told Matoro that if another Toa went corrupt and fell under his sway, he could use the Nui Stone to increase his power a thousandfold. Matoro tried to stop him but was put in a statis field. Teridax then was attacked by none other than Brutaka, who had spikes coming from his armor and a dorsal fin on his back. Then Brutaka snatched the Staff of Artakha and called for Botar to take it away, ruining Teridax`s plan. Brutaka and Teridax began to fight. Brutaka told Matoro to return to the other Mahri and he did, trusting Brutaka over Teridax. Teridax then attacked Brutaka, who easily countered Teridax's attacks. Brutaka convinced Teridax to leave and retrieve the Mask of Life, which was now in the hands of Hydraxon. Teridax left, knowing Hydraxon was likely to destroy the Ignika, but not before promising Brutaka that their battle wasn't over.

Teridax was next to Matoro after the short conflict between Hahli, Hydraxon, and Mantax. Wanting to get rid of Teridax/Maxilos, Matoro suggested to the Toa Mahri that Maxilos will track Hydraxon down. Without a choice, Teridax headed off in search for the jailer. Teridax managed to track him down. Hydraxon, thinking that Maxilos was still the Pit robot, asked the guardian to go with him in search of Mantax. When Teridax tried to persuade Hydraxon to stop following Mantax and capture the Toa Mahri and the other Barraki, and failed, Teridax/Maxilos attacked the jailer. Then Hydraxon summoned Spinax to attack Maxilos, only to find the Rahi being swiped away by the powerful being. Hydraxon then attacked Teridax using daggers, which was stuck directly on the armor's legs. Ripping the daggers out, Teridax roared at Hydraxon, and the sound blast knocked Hydraxon off his feet. Hydraxon managed to aim his Cordak Blaster at an undersea mountain, causing boulders to rain on Teridax.

Later On, Teridax got out of the avalanche, he had already been drifted off to the Razor Whale's Teeth. There, with Maxilos' body badly damaged, Barraki Takadox attempted to hypnotize Teridax into killing Mantax. Swiping Takadox aside, he was then attacked by Matoro, who froze him in a block of ice. The sudden decrease of temperature caused cracks to appear on the body, and Makuta's essence, the Antidermis, began to freeze. Later, during a fight against Hydraxon, Jaller's flames melted Maxilos' prison, and Teridax advanced towards the Mask of Life. However, Jaller slapped at the mask, and it spiraled upwards into Matoro's hands. To Matoro's surprise, Teridax did not launch any form of attack on Matoro, and simply watched as the two Toa disappeared.

Teridax then turned to confront the Barraki, revealing that he was not Maxilos and was actually the Makuta who had led to the Barraki's defeat. Anguished, the Barraki attacked Teridax, only to have four of their members defeated. Takadox then attempted to get out of the attack by showing Teridax the Betrayal Contract. Teridax then casted Takadox in a vision, displaying the Barraki's destiny. Unknown to Teridax, however, the other Barraki were slowly gathering their armies. By the time Teridax stopped casting the vision, the Barraki already assembled their armies and revealed to Teridax that they were pretending their defeat. They then summoned their troops of over 100,000 underwater Rahi against one.

Maxilos' body was greatly damaged after being attacked by the Barraki's armies. Pulling himself up from the fight, Teridax simply let the Barraki go, only wanting to delay them, and not destroy them. He felt the abrupt change when Mata Nui died, and knowing that it could not be the end, he prayed to himself in his mind that the Toa Mahri will continue their task to revive the Great Spirit so that his plans can succeed. Teridax later left the armor of Maxilos.

He then arrived at Artahka, from which he plans to work on the final task of his plan.

Dark Mirror
In the Toa Empire, Teridax wears an Infected Kanohi Hau because his Kraahkan is locked up in the Archives. Takanuva had encountered him in the form of Tuyet while searching of Krahka. He and the two other Makuta there, Krika and Kojol,agreed to help Takanuva to find Brutaka, provided that the Toa retrieve the Vahi from Jaller.

Teridax joined in the battle against Tuyet at the Coliseum, he was then forced to retreat due to the Toa of Iron and Plasma that had killed Kojol. However, he soon charged up his forces again, and combining with the efforts of Krika, managing to kill Matoran and Toa.

Personality
Teridax was arrogant and proud, desiring praise and devotion and becoming jealous when others got it instead of him. At the same time, he appeared to believe himself one of the good guys, justifying his actions as taken for the good of the universe. Upon being called a monster for his actions in the Great Cataclysm, he asked "I, a monster? For knowing my spirit brother, Mata Nui, required a good, long rest after his many labors? For offering my benevolent leadership to the Matoran in his absence? For saving Metru Nui from the threat of Nidhiki and Krekka?" - never mind that Mata Nui had not agreed to rest and that the Dark Hunters were only in the city at Teridax's invitation. Despite Teridax's apparent self-justification, series writer Greg Farshtey has described Teridax as a sociopath: "He has no conscience, he has no ability to feel remorse, and he feels no emotional connection to any other living thing. He would [notice Greg Farshtey was speaking about the "Makuta rulling the world" hypothesis] have been benevolent to the Matoran if he needed something from them, and then the next moment, he might have killed half a dozen just to break up the day."

Speaking to Vakama while pretending to be Nokama, Teridax revealed his perspective when he said, "We [Matoran] have to trust that those with more power know what is right for us all." When Vakama questioned whether wisdom came to Toa along with power, "Nokama" continued: "I was talking about real power, Vakama. Not the raindrops and wisps of breeze Toa produce. The power to shape the future ... the power to rule ... the power to change the lives of others for all time ... that is what I mean. ... It makes no difference what [those others] want. They will live in whatever world their superiors create for them, because it's all they know how to do. If Mata Nui had not wanted them herded, he would not have made them so easily led."

Greg has also said: "I think there was a time when Makuta was inspired and truly did want to help others -- but for the wrong reasons. I think that, just as Matau intitially saw being a Toa as all about the fame and the glory, Makuta saw what he was doing as something that would earn him the gratitude and devotion of Matoran. And it did, to a point, but nowhere near what they felt for Mata Nui. And that sparked jealousy and resentment in him that only grew worse as time went on."

Powers
Although once biomechanical, like most every other Bionicle lifeform, Makuta have since evolved into a form that's, as Thok put it, "just armor and energy - no organics, not anymore." Makuta need their armor in order to hold their energy together; if the armor is damaged then greenish-black energy will leak out and weaken them. Since his armor was completely destroyed, Teridax then existed merely as a mass of energy; but should too much time pass this energy would dissipate and he would die (it is unknown if it ever did).

Teridax's most commonly-used power was his ability to shapeshift, allowing him to shape his armor to any form he desired. The only limitation on this power was that when changing into a bigger, stronger form, he couldn't do it quickly unless he absorbed power and mass from somewhere. If what he absorbed was a living being, then their body was incorporated into his and their mind and spirit utterly destroyed (though not immediately - Teridax blamed his defeat in Metru Nui on having to suppress the minds of Nidhiki, Krekka, and Nivawk at the same time: "I disagreed with something I ate"). In his energy form, Teridax still had some limited shapeshifting power; he can make his energy liquid, gaseous, or even viral.

He controled the element of shadows, allowing him to manipulate shadow energy into different shapes such as spheres, beams, or hands. This power was strengthened by his Kanohi Kraahkan, the Mask of Shadows, which could fill others with fear and anger. However, due to the fact that his powers were based on shadow; light-based attacks against him proved to be especially effective.

Like all members of the Brotherhood of Makuta, Teridax was capable of creating slug-like beings from his essence called Kraata, which could infect Kanohi Masks and enslave those who wore the masks to his will. When exposed to energized protodermis, Kraata transformed into Rahkshi armor that another Kraata could control.

In addition to the powers described above, he also had 40 other powers. The strength of a stage-six Kraata should be considered the bare minimum when compared to a Makuta's strength.

List of Powers
Of these abilities, the only powers that Teridax could use when in his energy forms were the mental ones (like illusion or telepathy); he needed to have a physical shell to access the rest.
 * Accuracy - Can strike the smallest target at a great distance or in any environment or condition.
 * Adaptation - Instantly adapts to take maximum advantage of any condition or situation.
 * Anger - Has the power to turn even the Toa Nuva against one another in anger
 * Chain Lightning - Controls devastating bolts of chain lightning that leap between multiple targets.
 * Chameleon - Has the ability to become completely invisible in any environment.
 * Confusion - Extended proximity can reduce even a Toa Nuva to mindless babbling.
 * Cyclone - Has the power to create and control powerful cyclones at will.
 * Darkness - Has the power to consume all light in a large area; only Takanuva's light is stronger
 * Density Control - Complete control over own density and that of any object in physical contact
 * Disintegration - Has the power to reduce even protodermis to dust.
 * Dodge - Impossible to physically strike, no matter how swiftly or powerfully.
 * Elasticity - Can stretch incredible lengths in the blink of an eye.
 * Electricity - Powerful electrical field can be controlled to surround or stun distant objects or creatures
 * Fear - Has the power to bring fear to the hearts of even the Toa Nuva.
 * Fire Resistance - Strong enough to withstand the heat of Tahu Nuva’s magma swords
 * Gravity - Uses gravity control to crush any object in visual range
 * Heat Vision - Powerful long-range heat vision can ignite any object within sight
 * Hunger - Has enough strength to drain the energy of a Toa Nuva
 * Ice Resistance - Impervious even to the cold of Kopaka Nuva’s ice blade.
 * Illusion - Can create and control multiple realistic illusions anywhere within sight.
 * Insect Control - Powerful enough to control and command an entire hive of Nui Rama.
 * Invulnerability - Absolutely invulnerable to physical harm of any kind.
 * Kraata Creation - can create Kraata at anytime.
 * Laser Vision - Fires powerful eye-beams that can burn through solid protodermis.
 * Magnetism - Possesses magnetic powers strong enough to tear a slab of protodermis in two
 * Mind Reading - Powerful enough to invade the mind of a Turaga or Toa Nuva
 * Molecular Disruption - Has the power to utterly disintegrate any inorganic object with a touch.
 * Plant Control - Has total control over any plants in the area.
 * Plasma - Has the power to instantly melt any object into vapor
 * Poison - Dangerously toxic even to a Toa Nuva
 * Power Scream - Power Scream can shatter stone and can be heard all across the island
 * Quick Healing - Almost indestructible;can be used to heal the injuries of others
 * Rahi Control - Has absolute control over every living Rahi in the near area
 * Shattering - Has total control over its own shape, although its mass cannot change
 * Silence - Aura of silence is powerful enough to temporarily deafen a Toa Nuva
 * Sleep - Has the power to instantly put an entire village into deep sleep.
 * Slowness - Able to rob even a Toa Nuva of all speed as long as it remains nearby
 * Sonics - Blasts distant objects with powerful waves of sonic force
 * Stasis Field - Has the power to freeze a creature in near-permanent stasis through eye contact.
 * Teleportation - Has the power to teleport itself through any wall or other structure.
 * Vacuum - Has the power to create gale-force winds or instantly reverse their flow
 * Weather Control - Can manifest powerful, dangerous thunderstorms and blizzards at will

Known Forms
Due to his shapeshifting power, Teridax had fought against Toa in several forms. Here are the ones we know about, in chronological order:

Turaga Dume: Teridax secretly kidnapped Metru Nui's leader, Turaga Dume, and impersonated him for about a year and a half. This deception was not discovered until the Great Cataclysm.

"Ultimate Dume": When the Toa Metru confronted the false Dume, Teridax changed into this monstrosity by absorbing Nidhiki, Krekka, Nivawk and Metru Nui's power supply into his body. It was a giant, skeletal form with a humongous fanged mouth, giant claws, and wings. In the movie Bionicle 2: Legends of Metru Nui, this form was portrayed as his shadow titan form with Nivawk's wings. Its name comes from toy advertisements, as Lego did not want to reveal "Dume's" true identity before the movie was released. Ultimate Dume was 555 pieces.

Matoran: When first confronting the Toa Mata, he took the form of an infected Matoran. He did this to confuse the Toa, claiming that he was "that which the Toa had sworn to protect." He quickly switched into a more formidable form (see "Vortex form", below).

Vortex form: A swirling mass of mechanical pieces that used shadowy tentacles to attack. The "face" of this form appeared to be an infected Great Hau mask, which he had worn in his previous guise as a Matoran.

Shadow Titan form: This is Teridax's best known form, from when he challenged Toa Takanuva to a mock kolhii match. It was that of a large, armored being equipped with a two-bladed staff, and this was the only form so far which features the Kanohi Kraahkan in its true shape. Teridax here is 199 pieces.

Takutanuva:In the final battle between Teridax and Toa Takanuva, Takanuva attempted to tear the mask off of Teridax's face and the two ended up falling into a pool of energized protodermis. They ended up merging into a single being - Takutanuva.

Takutanuva's benevolent personality was mainly influenced by Takanuva rather than Teridax, for a few reasons. The first was that Teridax was not wearing his mask at the time, putting him at a slight disadvantage to Takanuva mentally. The second reason was that fusing with Takanuva and/or his Mask of Light had "enlightened" Teridax, giving him a clarity of thought that pierced the many lies he had told himself over the centuries.

Takutanuva immediately saw the will of the Great Spirit; that the Matoran were supposed to return to the city of Metru Nui. To that end, he went over to a huge stone gate in Teridax's lair and forced it open, allowing the Matoran to go through. As they did, Takutanuva stopped Hahli, who was carrying the mask of her recently-deceased friend, Jaller; and he (specifically, the "Makuta" half of him,being changed by the Mask of Light) infused the mask with his own lifeforce, bringing Jaller back to life. Unfortunately, this drain of power proved too much for Takutanuva; he could no longer hold the gate open and it came down and crushed him.

But the Mask of Light was thrown clear of the impact, and Takanuva's body was quickly restored in a beam of light. However, Teridax's armor was crushed and he was reduced to his energy form.

Takutanuva was one of the most powerful beings ever to exist, having light and shadow in perfect balance. He presumably had not only the powers of those two elements, but also the extensive list of powers that Teridax possessed. In the short time that he existed, Takutanuva demonstrated two abilities:

Immense strength: Takutanuva could, with effort, lift a stone gate so heavy that not even Teridax could move it.

Resurrection: Takutanuva could give up a good deal of his own lifeforce to restore life to the recently-dead; this was something that the frighteningly powerful Ignika could only do if another being sacrificed it's life force,spirit,and physical body to be turned into life energy,added to the Ignika's energy,and directed into the being that was recently deceased.

Antidermis: After his body was destroyed in the battle with Takanuva, Teridax existed only as energy. After telepathically influencing a gang of thieving Piraka who were raiding his lair, he shifted his energy to a viral form that the Piraka collected and called "antidermis" (though most of the Piraka were unaware of the virus' true nature). Matoran infected by antidermis were enslaved to the Piraka's will, similar to how infected Kanohi Masks once enslaved their wearers; while Brutaka temporarily became stronger and fiercer when he absorbed the virus. Antidermis had two notable weaknesses: infected Matoran could be cured with energized protodermis, and the Toa Inika's innate electrical energies protected them from infection.

Maxilos: When Axonn destroyed the antidermis vat, Teridax went into the black waters and took on the shell of Maxilos. When in this form he used Matoro to give him some of the Nui stone fragments in Tuyet's armor, and summoned Icarax to give him the Staff of Artakha. But then Brutaka took the staff and gave it to Botar. At some point he also fought Karzahni and won. This form was later almost disintegrated by armies of sea rahi. Maxilos (and Spinax together) is 267 pieces.

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