Crystal (Final Fantasy XV)

The Crystal is a powerful magical artifact in the world of Eos in the Final Fantasy XV Universe. It is a stone taller than an average human with a rough dark surface that has a crack on one side that lets one glimpse the glowing core. The Crystal's power is that of light and is a source of unmatched magical power. It is kept by the kingdom of Lucis and protected by the line of Lucian kings. According to legend, the Crystal is of divine origin and was bestowed to humanity alongside the Ring of the Lucii, which harnesses the Crystal's power for a chosen few.

Profile
Crystals are a recurring motif in the Final Fantasy series, and its most recurring concept, appearing in every installment. Crystals in Final Fantasy represent the power that sustains the world, and their power of light is often juxtaposed with darkness, which is sometimes shown as the emptiness known as The Void. The powers of light and dark tend to remain in balance and depend on each other, as The Void is the typical place of genesis for the crystals. In Final Fantasy XV the kingdom of Lucis (Latin for "of the light") is associated with the powers of light, but their royal color is black and the grim reaper is a royal symbol. The imperial lands are mired in the powers of darkness, but are associated with the color white.

The humans chosen to carry out the crystals' will are known as the Warriors of Light, who are always the main playable characters in a Final Fantasy game. In Final Fantasy XV the Crystal bestows its light to the line of Lucian kings.

In later installments crystals gained the role of being the collective souls for entire planets, with the souls of all living beings returning to the planet, such as in Final Fantasy VII and Final Fantasy IX. The Crystal in Final Fantasy XV is said to hold "the soul of the star", and at one point Noctis Lucis Caelum will be taken inside it.

Final Fantasy XV introduces the concept of the bonding of the souls via the Crystal, in which the Crystal links one's soul to those of his ancestors. This is seen with the Lucian kings who can wield the Crystal's magic by birthright, and who can each wield the combined powers of their forebears with the Ring of the Lucii. The "bonding of the souls via the Crystal" could also be seen as having a meta-element, of the theme of the crystal literally linking the series and its myriad Warriors of Light, and thus, also all the people who play the series.

As Final Fantasy XV started as Final Fantasy Versus XIII and part of the Fabula Nova Crystallis: Final Fantasy, elements of that subseries are present in its design. Souls appearing as floating immaterial crystal shards remains for Final Fantasy XV, now representing the power of the Crystal, the bonding of the souls, and the astral realm. Noctis's ten-year slumber inside the Crystal also hearkens to the concept of the crystal stasis in the Fabula Nova Crystallis games.

Story
Two thousand years ago, Ardyn Lucis Caelum was a Lucian king chosen by the astrals to save Eos from the Starscourge, a malady that transforms people into daemons. Ardyn absorbed countless daemons to save thousands across the world, yet was denounced by the astrals as unclean. He was denied entry to the astral realm and demonized by a jealous future king who later became chosen by the Crystal. As his transition rendered him immortal, Ardyn took the surname of "Izunia" and vowed to one day have his revenge on the True King's descendants and the Crystal.

Ardyn bides his time for millennia before establishing himself as chancellor to Iedolas Aldercapt, the Emperor of Niflheim and provides his knowledge to begin his plan for revenge.

The Crystal is implied to be the source of Lucis's rapid development in comparison to the rest of the world, but at the same time it drains the life-force of the king who protects it; he must shield it from outsiders by maintaining the Wall. Having conquered all other lands, bar Lucis, Niflheim reigns supreme, only repelled by those who derive their power from the Crystal.

Prince Noctis, the son and successor of King Regis, once recuperated in Tenebrae from a childhood injury. He met the young Lady Lunafreya of the Oracles' bloodline, who told him about his destiny as the Chosen King and the role of the Lucian kings as the Crystal's sworn protectors even if the Crystal and the light it provides for the world belong to everyone. Luna told Noctis that the Crystal's calling is to crown the King of Light who will save the world, and the eight-year-old Noctis promised he would do it without understanding the gravity of the deal.

The twenty-year-old Noctis is away from the crown city of Insomnia when Niflheim steals the Crystal during a supposed peace-treaty signing. Regis, Noctis, and Luna are pronounced dead. Luna survives with the Ring of the Lucii in her possession however, and Noctis begins a quest to rendezvous with her and reclaim the Crystal.

The Empire has been overtaken by the forces of darkness. It has begun to employ daemons in its army and experiment with them to create the magitek infantry, but this practice has spread the Starscourge plague to its populace that turns people into daemons the Empire cannot control. The Crystal is believed to have the power to banish daemons, seeing that it has always kept Insomnia safe. Though the exact reason the Empire steals the Crystal is never publicized, Aranea Highwind has heard the Empire believes the Crystal poses a threat to daemons. The Crystal only bestows its powers to the Lucian bloodline, however, and the Empire doesn't have the Ring of the Lucii. The Crystal is stored away in Zegnautus Keep, the magitek laboratory in the imperial capital.

Prince Noctis collects the Royal Arms of his forebears that lets him wield the power of kings. He forges covenants with the gods of Eos, the astrals, with help from Luna, and she passes on the Ring of the Lucii to him before her death. Luna was an Oracle said to also wield a power originating from the gods: she had the power to fight the powers of the dark, and without her holding the darkness at bay daylight is vanishing from the world with the Starscourge's advancement.

Wielding the ring as his weapon, Noctis infiltrates Gralea, but finds it devoid of human life and swarming with daemons and rogue magitek troopers; even the Emperor has turned into a daemon. When he finds the Crystal in the heart of the magitek lab, he asks for its power to save the world but to his surprise is absorbed inside it. Noctis enters an otherworldly realm inside the Crystal that is bathed in light.

He encounters the astral god Bahamut who explains to him that the Crystal holds the soul of Eos. Bahamut explains that Noctis has the power to banish darkness from the world as the True King at the cost of his own life. Gradually the power of the Crystal concentrates as the Ring of the Lucii becomes more powerful with every Lucian king's spirit. With King Regis's passing Noctis could wield the full powers of the Crystal—power even greater than that of the gods'—and become the True King. Noctis sleeps inside the Crystal for ten years, during which time he absorbs the power he needs to fulfill the prophecy. After Noctis disappears the sun doesn't rise again and the world is overtaken by daemons.

The exact nature of the astral realm inside the Crystal is never explained, but where Noctis meets Bahamut is described as the "heart of the Crystal", and thus the soul of the world. When he returns ten years later, Noctis makes his way to the ruins of Insomnia to where Ardyn has taken the Crystal. Ardyn ushers the heretical astral Ifrit upon Noctis and his friends. Ifrit despises mankind and is the origin of the Starscourge plague and the daemons, but Noctis prevails with the help of the other astrals, including Bahamut.

Noctis confronts Ardyn in the throne room where the Crystal is mounted on the wall atop the throne upon which Ardyn is sitting. Noctis kills Ardyn and then calls upon the spirits of past Lucian kings to be able to confront Ardyn's spirit in the afterlife. The spirits of the old kings attack Noctis until his soul is taken by the ring, and his spirit enters a realm of full of light similar to the place inside the Crystal where he had met Bahamut. Noctis uses the power of light to banish darkness from the world and erase Ardyn's soul. The Ring of the Lucii disintegrates and the sun finally rises.

With the Lucian bloodline ended and the Ring of the Lucii gone, it is unknown what becomes of the Crystal after the prophecy of the True King has been fulfilled. With both the Lucian kings and the Oracles gone, there is no one left to wield divine power in Eos.

Musical themes
The track "In the Light of the Crystal" plays in the vicinity of the Crystal. It is a version of the traditional Final Fantasy crystal theme, the "Prelude".

Creation and development
The Crystal was part of the story ever since the game was known as Final Fantasy Versus XIII. In the earliest materials it was implied that every nation once possessed a Crystal but lost them due to warring over them, the only one remaining being Lucis's Crystal. It hearkens to the traditional Final Fantasy storyline of the different nations of the world protecting their own Crystal. In Final Fantasy XV, there is only one Crystal, and it gains properties introduced later in the series as the world's soul.

Trivia

 * The Ring of the Lucii has a small clear gemstone in the grasp of the armored figure on the ring's front. Whether this is a shard of the Crystal of Lucis is unknown. The ring allows one to channel the Crystal's powers.
 * An evil empire stealing the crystals is an archetypal Final Fantasy storyline, which is also reprised in Final Fantasy XV.
 * King Regis appears to talk to the Crystal in the Omen short film, although he voice that answers to him is likely Bahamut's.