Elemental Wraith

The Elemental Wraiths were beings of immense, god-like power which were worshipped by the Argenta, the peoples of Argent D'Nur, and are significant in the backstories of Doom (2016) and Doom Eternal, but are mainly only described in the Codex. The Night Sentinels, the elite military of the Argenta, served as both guardians of the Wraiths, and as a contingent against their unpredictable wrath. In the fall of Argent D'Nur, the Wraiths were slain by the Hell priest Deag Grav, and their souls were used to forge the Well, another source of Hell's Argent energy. Another name given to the Wraiths was the "Firstborn".

Ancient history
The Wraiths are credited with the creation of life on Argent D'Nur. They were released by (or from within) a giant impactor known as the Cosmic Spear which struck the planet in primordial times and accelerated the evolution of life. Wraithcall, the mystic power of the beings, could awaken monsterous giants known as the Ancestrals, against whom the Argenta struggled for their continued existence.

After attaining mastery of their world, the Argenta immersed themselves in the study of Wraithcall and were able to derive magic from this study. This lead to the formation of a priesthood known as the Order of the Deag.

Study of the Wraiths also yielded a potent form of energy which came to be known as Sentinel Energy, which powered all of their technology. When the Maykrs later introduced themselves to the Argenta, worship of the Wraiths was replaced by worship of the Maykrs. Because of this transition, the beasts were put to slumber, though the Argenta continued to channel their energy, as evidenced by the Crucible blades which are made of "Wraithfire," as well as widespread use of blue flame lamps and the Sentinel battery.

Creation of Argent energy
After the arrival of the Outlander, who later became the Doom Slayer, the Khan Maykr discovered Hell's existing energy, derived from the souls of its victims. Acting in concert and in secret with the Order of the Deag and legions of Argenta slaves, the Nekravol was constructed in Hell, a massive factory which combined Hell's energy with the energy of the Wraiths, refining Hell's essence into Argent energy. When the Night Sentinels discovered the Khan Maykr's pact with Hell, they splintered, with the loyal Sentinels returning to Wraith worship, despite the Wraith energy being weaker than the Argent used by the Ascended Empire of the Maykrs. This began a period of strife and civil war amongst the Argenta.

Destruction
After secretly betraying their people in service of the Khan Maykr and becoming the Hell priests, members of the Order of the Deag created a trap for the elite of the Sentinels during the chaos of the ongoing civil war. The Deag were able to corrupt one of the elite, the Betrayer, by tormenting him with images of his son who had been lost in battle against Hell. By promising the return of his son, he was persuaded to lead the Hell priest Deag Grav to the current location of the Wraiths at the Elemental Sepulchre.

Using the power of the demonic Crucible, Deag Grav killed the Wraiths and forged their souls into small orbs, from which their energy perpetually flowed. This created a massive source of the energy known as the Well, which Hell took for its own means, instigating a period in that realm known as the Ascension. Much later, the Doom Slayer would return to Argent D'Nur and laid the souls of the Wraiths to rest, destroying the Well.