The Order of the Deag was founded in the earliest days of Sentinel civilization and were tasked to pay tribute to the Wraiths and appease their tempestuous hunger. During the Time of Grief, the Argenta shifted their worship of the Wraiths to the Maykrs, and the Order of the Deag began to preach the teachings of the Khan Maykr.
During the reign of King Novik, the Order judged an unknown outlander by having him sent to the Arena. This outlander proved his innocence in battle and would eventually earn the title of "Doom Slayer." Sometime after the arrival of the Slayer, the Sentinels came under attack by demons from Hell. The Deag Priests were ordered by the Khan Maykr to study the demons to find any means to defeating them. Their research led to the discovery of Hell Essence that empowered the demons and they used this demonic energy to combined with Sentinel Energy from the Wraiths to create Argent Energy, which benefits the longevity of the Maykrs and creating powerful weapons to be use against Hell. However, the Deag priests fell to the temptations of Argent Energy as they learned that its creation is made from the tortured souls of mortals, and they agreed with the Khan Maykr's plans to forged an unholy pact with Hell's Dark Lord to build Soul Spires in Hell's realm to harvest mortal souls into Argent Energy in exchange for Hell expanding their dominion.
The conspiracy between the Maykrs and Hell was eventually discovered by the Night Sentinels which led to a civil war between the Sentinels. The Deag Priests escaped from suspicions and feigned loyalty to the Night Sentinels and Wraiths. In time, the High Priests tricked the Night Sentinels into launching an invasion into Hell that trapped them and split their forces, allowing the demons to kill them to the last man - except for the Doom Slayer. The High Priest Deag Grav also tricked the Night Sentinel Valen into betraying his order by giving Hell's access to the Wraiths with the false promise of resurrecting Valen's dead son by turning him into the Icon of Sin.
Since the fall of the Argenta, the Deag priests became known as "Hell Priests". Becoming wielders of dark arcane magics to suit their insidious purpose, they use their unholy powers to coordinate Hell's forces and increasing their battle effectiveness, harvesting the blood of mortals to be use in their occult rituals, corrupting mortals to serve Hell, and overseeing the conquest and transformation of viable planets into Argent Energy.
The Hell Priests were tasked in leading the Hell invasion of Earth under the commands of the Khan Maykr. While preparing Earth for the final Blood Ritual that would consume the planet, their efforts are thwarted by the Doom Slayer. Deag Nilox became the first to die at the Slayer's hands in which his decapitated head was presented before his colleagues Grav and Ranak. The Khan Maykr then transported the remaining Hell Priests to safety; Grav was sent to Sentinel Prime, and Ranak was sent to the UAC Arctic facility.
The Slayer traveled to the Arctic facility to confront Ranak, where the Hell Priest unleashed Doom Hunters on the Slayer. However, Ranak's cybernetic demons were no match for the Slayer and Ranak was decapitated while futilely pleading for his life. The last Hell Priest took shelter in the Arena where he awaited the Slayer and unleashed The Gladiator against him. The Gladiator was slain and the Slayer killed Grav by blowing his head off.
- It is noted that the Hell Priests' souls were 'guarded', a protection that the Slayer overcame via arcane medallions. It is unknown how he obtained the medallions he used on Nilox and Ranak, but he gained another by killing the Gladiator. It is also unknown if this 'protection' means that the Priests were immortal or that they would simply be resurrected by Hell after their death.
- History of the Sentinels - Part I
- History of the Sentinels - Part II
- History of the Sentinels - Part IV
- History of the Sentinels - Part VII
- History of the Sentinels - Part VIII
- Fuel the Eternal Flame - Part II
- History of the Sentinels - Part XIII
- Story of Hell: Hell Priests
- Story of Hell: Hell Barges