For those who have not completed games in the Xenoblade Chronicles series, this page contains spoilers regarding the plot. Discretion is advised.
The Aegises (天の聖杯, Ten no seihai, lit. Heavenly Holy Grail) are legendary Blades in Xenoblade Chronicles 2. They are Blades born from the cores of the Trinity Processor. The existence and power of the Aegises form the basis of the story.
The Aegises are Blades that bear Core Crystals similar in shape to the Conduit, from which they draw their powers, though Mythra and Malos have different abilities. Mythra's abilities include foresight, while Malos can destroy matter. In her ascended state, Mythra is also capable of light speed travel. When using their full power, Aegises are able to rewrite the physical rules of their surroundings
The shape of an Aegis' sword varies; Malos' appears to be a Monado, while Pneuma's, Mythra's, and Pyra's swords do not, though Pneuma's has a ring at the base of the blade similar in design to a Monado.
Aegises do not follow many of the same rules as Blades awoken from normal Core Crystals. For example, they can live after their Driver's death, while other Blades are reverted to their Cores. Aegises can also resonate with Blades of their own, as seen when Malos fights alongside Sever. An Aegis' Core Crystal also contains information about every living being's genetic code, which may explain why they can act as Drivers.
Aegises also exhibit a degree of control over the Artifices; Amalthus refers to the Artifices as "servants of the Aegis." Mythra is able to control her own Artifice, Siren, and during the Aegis War, Malos commanded hundreds of Artifices, including one similar to Siren. Both are able to activate and control Artifice Aion, though neither can control Artifice Ophion without the use of the Omega Fetter.
- Main article: Xenoblade Chronicles 2 (plot)
The Core Crystals that came to be known as the Aegises originated as the three cores of the Trinity Processor, a powerful computer aboard the First Low Orbit Station, known as Ontos, Logos, and Pneuma. After Klaus used the Trinity Processor to perform his experiment to create a new universe, it resulted in the devastation of the original universe, and he created the world of Alrest in the image of the previous world, becoming known by the people of Alrest as the Architect. When creating the Blades, the Architect planned to repurpose the three cores of the Trinity Processor with the task of relaying information to and from the Blades to help them adapt; however, as Ontos previously disappeared in an interdimensional accident, only Logos and Pneuma were left to monitor the Blades. All data collected by the Aegises are passed onto the Architect.
- Main article: Aegis War
Eons later, Amalthus, an Indoline who was disgusted by the world and the people who inhabit it, climbed the World Tree in hopes of finding the Architect. When he reached the top, he found Elysium empty, save the two cores of the Trinity Processor. He took them back to Alrest with him as proof that he reached Elysium. Once he returned, Amalthus awakened Logos, who became known as Malos. Inundated with Amalthus' hatred for the world, Malos developed similar sentiments and promptly began an assault on the world of Alrest under the guise of serving the Architect's will. Malos adopted the title of "the Aegis" for himself from an Indoline artifact said to embody the Architect's light.
Malos soon separated himself from Amalthus, no longer bound to him like most Blades were to their Drivers. In response, Amalthus searched the world for someone who could awaken Pneuma to counter Malos. While Prince Zettar of the Kingdom of Torna tried and failed to resonate with the core, his nephew Addam successfully awakened Pneuma, who took on a weaker form called Mythra. With both Mythra's aid and the recruitment of many other people from around Alrest, such as Lora and her Blade Jin, Addam led a campaign against Malos that would later be known as the Aegis War. Though Mythra eventually defeated Malos, the world of Alrest suffered immense casualties, as three Titans, including Torna and Coeia, were killed in the process. In her anguish and despair after accidentally killing the Tornan Titan, Mythra created her alternate personality and "sister" Pyra before sealing herself away, while Addam plunged Pyra deep into the Cloud Sea until someone worthy of her power appeared.
Amalthus, now Praetor of the Indoline Praetorium and unaware of Addam and Mythra's whereabouts, laid waste to the remaining Tornans on Spessia in an effort to destroy the remaining Aegis out of fear of her power. The casualties included Lora, who was "eaten" by Jin; this made him a Flesh Eater and allowed the two to a chance to stay together.
Malos was assumed to have been slain by Mythra in a sea of fire during the war, though he managed to survive, albeit with significant damage to his Core Crystal. This damage caused him to lose many of his Aegis powers. Approximately five hundred years after the Aegis War, Malos returns to Alrest and finds a desolate Jin, now having a similar view of humanity as Malos, in a city during a heavy downpour, and the two decide to join together.
Reawakening of the Aegis
Five hundred years after the Aegis War, the terrorist organization known as Torna, led by Malos and Jin, approaches Chairman Bana of the Argentum Trade Guild in need of a Leftherian salvager for a high-paying job. Rex ultimately accepts the offer, and he helps bring up an Ancient Ship. Locked behind a seal that only a Leftherian can open is Pyra. Although Torna seeks Pyra for their own reasons, Rex inadvertently becomes Pyra's Driver and is slain by Jin in response. Meeting in Pyra's dream of Elysium, Pyra offers to revive Rex by giving him half of her Core Crystal in exchange for him taking her to the real Elysium. Once Rex is revived, the two combat Malos and eventually escape. Rex slowly begins to learn bits and pieces of Pyra's past. Throughout their journeys, Rex and company encounter many who wish to either use Pyra's power for themselves, such as Dughall, or destroy her altogether, such as King Eulogimenos.
Malos, alongside Akhos, meets Cole in Fonsa Myma and offers him a way to rejuvenate his life force, but at a cost. Cole refuses, though his granddaughter Iona follows Malos and asks him to help. He then talks to Pyra in a dream in Elysium and reveals that to save Iona, she must come to the Olethro Playhouse alone. The party wakes up the following morning and follows Pyra to the playhouse. Vandham sacrifices himself to allow Rex and Pyra to escape, though Rex refuses to let Vandham die in vain. In a last ditch effort, Mythra then awakens and uses Siren's power to destroy Akhos' and Malos' Blades. Malos then uses his remaining Aegis powers to escape the playhouse.
The next day, Pyra reveals to the party that Malos is an Aegis as well and tells them about the Aegis War. Their quest to climb the World Tree and reach Elysium eventually sees them working with Amalthus once more, who supports Rex on his quest to save Alrest, though his motives seem somewhat unclear. Mythra states that Amalthus still hasn't gained her trust. After Fan la Norne's death, Malos begins to question whether his hatred for the world is truly his own or someone else's.
Taking of Pyra
Rex and company then journey to Tantal, where the Omega Fetter is being kept. The Fetter can be used to control Ophion and potentially open the path to the World Tree. After Rex and company acquire the Omega Fetter, Torna intercepts them at Genbu Crown, and Jin unleashes his true power and easily defeats Rex and Mythra. Before Jin is able to remove Rex's portion of the Aegis Core Crystal from his chest, Pyra threatens to kill herself using Siren's targeting ray if Jin kills him. Jin draws his sword, and Pyra willingly gives herself and the Omega Fetter over to Torna, much to the party's objection.
On board the Marsanes, Malos tells Akhos that an Aegis Core contains data on all existing life forms; it is for this reason that Pyra gave up half of her Core to heal Rex's heart. He also reveals that Aegises can exist for a short time without their Cores, and that she likely would've given her full Core to Rex before having Siren kill her. Malos and Jin later take Pyra to the Cliffs of Morytha, where he begins stealing data from her Core to repair his own; in the process, he learns about Artifice Aion's existence. They also are able to use the Omega Fetter and make Ophion fall under their command.
The Third Aegis Sword
After the battle, King Eulogimenos calls in Rex to his Royal Audience Hall to inform him of a Tantalese legend. In a book recording the deeds of Addam, a third Aegis sword is mentioned. Addam himself was unable to control its power and thus sealed it away in an unknown location. Azurda leads Rex and the party back to Fonsett Village, where he reveals that the Village was founded by Addam; Azurda was tasked with guarding the village, which holds the entrance to Spirit Crucible Elpys, the location of the third Aegis Sword.
The party ventures deeper inside Elpys, despite the powers of their Blades being weakened. At the Vault of Heroes, they confront an endless wave of apparitions that take the form of Addam. After seeing Rex's pure motives, Addam speaks to him in a dream in the fields of Elysium, telling him that to be the true driver of the Aegis, he must take on all of her burdens. The third sword is presented to Rex, though it soon disappears from his hand.
Confrontation at Morytha
The group travels to the Cliffs of Morytha, where Pyra is being kept. They soon run into Malos, who siphoned Pyra's Core Crystal to repair his damaged Core Crystal, stealing her memories in the process. Now having all of his Aegis Powers once again, he challenges the party to a battle with a Monado-like sword but is temporarily subdued by Nia.
The party meets Jin and Malos again at the Gotrock Oracle Ruins, where Malos hands over Pyra's seemingly lifeless corpse. During the battle against the two, Pyra and Mythra ask Rex to move on, believing Alrest would be better off without their dangerous powers. They also reveal their reason to reach Elysium: to beg the Architect for death. Rex refuses to break his promise and reassures them that together, they can find their place in the world. This causes him to become the Master Driver and summon the third Aegis Sword. Pyra reawakens and takes on a new form with long, green hair and a silver outfit, and has the Greek word "πνεῦμα" written on her chest; she gives Rex a similar outfit. With this new power, they easily defeat Jin and Malos.
Malos then reveals his true motives: by climbing the World Tree, he can kill the Architect and use Artifice Aion to destroy the world, claiming it to be an Aegis' responsibility to do so. Using the Omega Fetter, he commands Ophion to attack the party; Pyra summons Siren, and a brief skirmish between the two destroys the ruins. After landing in the Land of Morytha, Mythra assumes her ascended state in order to heal Jin. While traveling through Morytha, Jin reveals Torna's and Amalthus' pasts.
Climbing the World Tree
Malos and the rest of Torna pilot the Marsanes down to the Land of Morytha and retrieve Jin, leaving the others to climb the World Tree from inside. When the party reaches the base of the World Tree, Pyra once again transforms into her ascended state and activates an elevator upward, stating it was instinctual. Jin and Malos eventually leave the Marsanes and continue climbing the World Tree as the remaining members of Torna fight off Indol. Jin eventually stays behind to fight Rex while Malos continues upward.
Upon reaching the exterior of the World Tree, the party witnesses Indol's attack on the Marsanes. Using Fan la Norne's core crystal which he implanted in himself, Amalthus attempts to control Mythra to summon Siren and destroy the Marsanes, though Mythra resists, stating that Rex is her true Driver. With the help of Poppi, Rex and Mythra get close to Indol, and Mythra assumes her ascended state to attack Indol's amplification towers and prevent Amalthus from controlling blades.
When reaching the Megrez Gateway, the party confronts Amalthus once more, where he reaffirms that it is the Aegis' job to destroy the world. The party realizes that Malos' beliefs and hatred of the world stems from Amalthus. Jin helps the party defeat Amalthus and tells Rex to stop Malos.
Malos is the first to reach Elysium and meet the Architect, who addresses him as Logos. The Architect tells Malos that he is already dying, which causes Malos to spare his life and instead activate Aion, to which the Architect doesn't object.
When the party reaches Elysium, the Architect reveals his identity as Klaus and explains the creation of Alrest and the Aegises. He also reveals Pyra and Mythra's true name, Pneuma. Klaus tells the party that his other half will soon die, causing him and the Conduit, which gives the Aegises their powers, to disappear. Given new hope by the unique bond shared by Rex and Pneuma, Klaus leaves the fate of Alrest in their hands and sends them off to stop Malos and Aion.
The party encounters Malos at the Aion Hangar, where he reveals that although he may have developed a hatred for the world from Amalthus, his beliefs were strengthened through Jin's suffering. He powers up Aion and pilots it against Rex and Pneuma as the other Artifices, under Malos' command, attack Alrest. Through directing a beam of Siren's particle cannon into the Aegis Sword, Rex and Pneuma defeat Aion and damage Malos' Core Crystal. Malos begins to fade away and the Artifices end their assault.
After Malos passes on, the World Tree begins to collapse due to the Conduit's disappearance. To prevent the World Tree from destroying Alrest, Pneuma stays behind to use Aion's remaining power to self-destruct and destroy the World Tree, much to Rex's objection. Pneuma gives the remaining half of her Core Crystal to Rex, and the remaining party members evacuate the World Tree while Pneuma is supposedly killed in the explosion. Before her death, Malos' voice is heard, asking her how it was being alive.
After reaching the new land revealed to them by the Architect, Pneuma's Core Crystal begins to flash again before summoning a large pillar of light. The light fades away to reveal Pyra and Mythra, alive, now in separate bodies.
- Its name likely refers to the aegis, the mythological shield of the God Zeus in Greek Mythology. In some traditions, the shield was made from the skin of Amaltheia (Greek: Ἀμάλθεια, tender goddess), the foster-mother of Zeus, from whom the name of Amalthus may come.
- The USB Deluxe Edition of the Xenoblade 2 Original Soundtrack is a gold-colored USB stick shaped like an Aegis's core crystal, inscribed with πνευμα (pneuma), based on the ancient Greek word πνεῦμα/πνεύμα.
- During the game all but the True Aegis Sword are broken; Pyra's is broken at the Ancient Ship and reforged upon her bonding with Rex; Mythra's is broken at Genbu's Crown and is recreated with the True Aegis as the base; and Malos' is destroyed after his defeat at the Aion Hanger.
- The ability of the Aegises to rewrite physical rules is very similar to how Alvis describes the Monado in Xenoblade Chronicles, as a "sword capable of disturbing the very fabric of existence".
- In Xenoblade Chronicles: Definitive Edition, the key of Alvis' necklace is replaced by a crimson crystal that resembles an Aegis core.