Etro's gate

Etro's Gate, also known as the Unseen Gate, is a gateway to the afterlife in Fabula Nova Crystallis: Final Fantasy. It is referred to as Door of Souls in the analects in Final Fantasy XIII and is operated by the goddess Etro.

According to the official mythology, the universe is divided in two halves: the visible world, or the world of the living, and the Unseen World, or the world of the dead; and if the balance between the two worlds is broken, the universe would be in danger of collapsing. Regardless of this fact, Bhunivelze and his fal'Cie creations are compelled to find the gate to ensure the former becomes immortal.

XII. The Door of Souls
''When our earthly vessels meet their end, the souls they housed must leave this world. Would the path of their migration not be the same one as our departed gods? Must they not pass through the same doorway the Divine employed to reach that place that lies beyond?''

''If this is the case, it stands to reason that, should a great many lives at once be cut short, a flood of souls would surge through the aforementioned portal. The Door would be thrown wide, and perhaps we might even glimpse the gleaming light of Divinity beyond.''
 * —On the Nature of Fal'Cie

XIII. Fabula Nova Crystallis
''Children of Hallowed Pulse scour earth, searching substance for the Door. Those of Fell Lindzei harvest souls, combing ether for the same. So have I seen.''

The Door, once shut, was locked away, with despair its secret key; sacrifice, the one hope of seeing it unsealed.

When the twilight of the gods at last descends upon this world, what emerges from the unseeable expanse beyond that Door will be but music, and that devoid of words: the lamentations of the Goddess Etro, as She sobs Her song of grief.
 * —Author unknown

Etro's Gate
''The instant Etro's Gate opened, a world-devouring darkness slipped through from Valhalla. The goddess turned back the river of time and that terrible darkness—the Unseen chaos—was sealed away.''

''Her power exhausted, Etro fell into a sleep from which she would never awaken. It was Lightning who sensed that someone meant to exploit that weakness and destroy the goddess for good. She learned of the man named Caius Ballad.''

''If the goddess is destroyed, the chaos of the Unseen Realm would be unleashed, and the mortal realm devoured by Valhalla. Lightning decided to stand and fight, to protect Etro and see her benevolent will upheld.''

Final Fantasy XIII
Upon a person's death, what could be called their "soul", turns into crystal energy and passes through the gate to the afterlife. The fal'Cie, being machines, lack souls and thus could not access Etro's Gate. The fal'Cie believe the Maker, the god who created the world of Final Fantasy XIII, has departed and gone beyond Etro's Gate somehow.

The fal'Cie devise a plan to send as much crystal energy through the gate as possible, by destroying Cocoon, believing the massive amount of deaths would force Etro's Gate wide open, and reunite them with their Maker while the world will be reborn. However, this act would destroy the balance of the world and Etro stopped the first attempt during the War of Transgression.

Lightning's group first hears of the plan from Cid Raines in the Fifth Ark. Later, before ascending to Edenhall, the party can observe crystal energy glimmering in the air. They wonder of its significance, which is when Barthandelus appears to them in the guise of Galenth Dysley. He explains it means the Maker is soon to return, and as Barthandelus leaves and disappears inside the tower above Edenhall, Etro's Gate opens on the sky of Eden.

Later, after the party defeats Orphan, the lights of Cocoon go out, all but of the mysterious light that is Etro's Gate. As Ragnarok crystallizes the world of Cocoon, Etro uses her power to free the Pulse l'Cie of Cocoon from their fate before the gate completely closed.

The gate itself is only ever mentioned in the two final Analects, and in the battle theme "Born Anew", whose translated lyrics spell, "l'Cie, you promised to open the gate, full of eternal light!"

Final Fantasy XIII-2
Immediately after the events of Final Fantasy XIII, as a result of Etro freeing the l'Cie of their fate, chaos leaks into the visible world and drags Lightning through the Historia Crux to Valhalla, while at the same time, warping the timeline.

During Lightning's battle with Caius Ballad, Noel Kreiss emerges from the Gate over Etro's temple and falls towards Valhalla causing Lightning to go rescue him atop a summoned Bahamut. Later, meeting with Noel and Serah at New Bodhum in the year 700 AF, Lightning tells them the nature of Etro's Gate and how Caius seems intent on finishing what the Cocoon fal'Cie started in the slaughter of Cocoon's people to force Etro's Gate to open wide.

The gate appears again before the final battle with Caius. In his Chaos Bahamut form, Caius flies through into Valhalla, followed by Serah and Noel. After defeating Caius and solving the final paradox, they emerge from the Unseen Realm using a Time Gate. At the end of the game, Etro's Gate is smashed apart by the chaos that is no longer bound by goddess Etro, and chaos enters the mortal realm.

Final Fantasy Type-0
Arecia Al-Rashia's reasons for creating Class Zero is in order to use the power of a soul with great power to force Etro's Gate to open. However, serving Lindzei in opposite to Arecia being a servant of Pulse, the Lulusathian Judge believed that the sacrifice of billions would be a better method and sends his forces to slaughter everyone when Finis begins.

After they both failed, Arecia would then reset the whole world and prepare for the next experiment. The two have been continuing their experiment 600,104,972 times before Arecia finally decided to end it and leave Orience forever.

Final Fantasy XV
Etro's Gate is the gateway to the afterlife. Legend has it that upon a person's death, they will meet the goddess at the gate, who will open it and let the soul pass onto the afterlife. Etro is thus known as the Goddess of Death.

Through this theological occurrence, near-death experiences are also steeped in the legends and lore of Etro. When one does experience dying and one's soul pulls back from the borders of mortality and life afterwards, upon seeing the light of the opening gate, they are said to gain the graces of the Kingdom of the Dead, and are bestowed with a great power. It is stated that very few are actually granted this power. Noctis Lucis Caelum and Stella Nox Fleuret are said to have this blessing through their experiences.

Music
"Etro's Gate" is a track that appears in Final Fantasy XIII-2 and was composed by Masashi Hamauzu. It plays during the FMV of Lightning being trapped in a paradox and falling through the Historia Crux. It noticeably has the slow-paced melody of "Blinded By Light" included in several moments.

Trivia

 * A replica of Etro's Gate is actually seen behind the final form of Orphan in Final Fantasy XIII. During battle the camera can move in a way to let the player get a view of the structure, but the edges of it can be seen from any angle. When viewed from the front, Orphan's body and the gate form the appearance of an eye.
 * The presence of Etro's Gate appears to be accompanied by flashing crystal shards in the air. This is seen in Final Fantasy XIII where crystals begin to glow in the air as Etro's Gate opens on the sky. The same phenomenon is seen in Final Fantasy XIII-2, where the air glimmers with crystals when Lightning is met at the pier, having entered from Valhalla. The same phenomenon also appears to be present in Final Fantasy Versus XIII where the glimmering crystals have been seen in trailers, and the legends say it is the light that can be seen when someone is near death.