The Veil

The Veil is a paracausal entity affiliated with the Traveler. Its existence was revealed to the Guardian by Rasputin in his final message, stating it resided in a hidden Neptunian city and that it was of immense paracausal power. It is used by Neomuna as a power source for the city, and the paracausal energy field it projects forms the basis of Neomuna's CloudArk.

Overview
The Veil somewhat resembles a plant or jellyfish, with a bulbous main body, branching root-like tendrils that can rapidly grow and generate an indestructible dome, and a large, brightly glowing white hole underneath. Seen from above, it seems to have a circular "canopy", resembling an energy field decorated with intricate blue and purple patterns.

History
The origin and true nature of the Veil remain unclear; it is unknown if it was created by the Traveler or accompanied it when it arrived in the Sol System, and its precise connection to the Traveler has yet to be revealed. Nezarec describes it as the "the sapid secret of the Witness' first victims," suggesting that it may be connected to the Witness' origins.

It has long been of interest to the Vex of the Sol Divisive, who attempted to create a Darkness-infused facsimile in the Black Garden - the equally mysterious entity that would later come to be known as the Black Heart.

The Collapse
During the Collapse, the Disciple of the Witness known as Nezarec led the Black Fleet's assault on Earth, and managed to secure the Veil on his Pyramid. However, he was betrayed by Savathûn, who killed Nezarec, cursed his remains and spirited the Veil away to Neptune.

The Veil would later play a central role in the founding of Neomuna, serving as the main power source for the city and the basis of its CloudArk infrastructure. An Ishtar Collective facility was constructed around it, to study it and keep it safe.

Lightfall
On the orders of the Witness, Calus and his Shadow Legion invaded Neomuna and attempted to use the Radial Mast to establish a link between the Veil and the Traveler. They were ultimately unsuccessful, but following Calus' defeat the Witness was able to link with the Veil by taking control of the Guardian's Ghost, which caused the Veil to emit an energy beam that allowed the Witness to open a portal on the surface of the Traveler.

Trivia

 * A number of pre-Lightfall Lore entries make reference to a mysterious "veil", which may or may not refer to the Veil itself:
 * The Lore entry 'Reextinction' contains a dialogue between the Nine in which they make reference to "laying themselves bare before the veil".
 * The Lore entry "Irrealis" contains the phrase "somewhere, a veil is always lifting" in reference to the timeless nature of the Black Garden.
 * The Lore entry "The Witch" describes a "falling veil" that will soon snuff out the Light of Guardians.

List of appearances

 * Destiny 2
 * The Witch Queen
 * Season of the Seraph
 * Lightfall