After missing for a long time, Doom Slayer returns while humanity is on the verge of extinction by the evil invaders.
What happens when Doom Slayer is absent?
After being deceived by Samuel Hayden and stealing the Crucible sword at the end of Doom (2016), we do not know what happened to Doom Slayer between then and when Doom Eternal started. All we know is that Samuel Hayden brought the Crucible back to Earth to be used as a source of energy to prevent the crisis in the human world. His efforts were destroyed when the remnants of the cult Olivia Pierce created summoned demons on Earth, causing UAC to become schizophrenic.
Those loyal to Samuel and him split up to form ARC to fight the demons, while those who remained in UAC became cults under the Deag clerics who had betrayed Argent D'Nur, Old Night Sentinel and Doom Slayer. Samuel Hayden's efforts to resist and the remnants of the Earth army are not really effective - they spend most of their time . losing, and the demons constantly eat the Earth, making it a part of Hell.
Then one day, the Doom Slayer unexpectedly returns on the Fortress of Doom - a spaceship / fortress created by the Argentinians in ancient times. We don't know how it fell to the Doom Slayer, but he used it as his base and embarked on his work quietly. If you want to ask what that job is, the answer is to destroy the evil demons and bring revenge to those who betrayed him and his Night Sentinel comrades years ago.
Back to revenge
In order to root out the evil's presence on Earth, the Doom Slayer needs to destroy the three Deag clergy - now Hell Priest - who are hiding somewhere on Earth. With the help of VEGA in the role of AI controlling the operation of Fortress of Doom, Doom Slayer began hunting for his goals. His first target was Deag Nilox hiding in a stronghold in Los Angeles - USA, and the missionary could not believe his eyes when he witnessed the sudden appearance of Doom Slayer. He introduced him to the knife on his left arm after many years of not meeting.
After finishing Deag Nilox, Doom Slayer takes him with him to the conference of the hell clergy. They told Doom Slayer that his actions would not solve anything - even if they were all killed, the Earth and its creatures would be sacrificed to Khan Maykr to restore the lineage. Argent energy that Khan Maykr needed to maintain his existence. Khan Maykr also appeared to try to convince Doom Slayer that by giving his life to Urdak, humanity could atone for the sin, that 'you cannot resist Khan Maykr's will.' and reiterating her old propaganda, that Doom Slayer was a tool created by Khan Maykr to bring Maykr's teachings to the superstitious, and punish those who dare to harm him. follow the path that Maykr taught.
You know what will happen later. Doom Slayer will prove he can completely resist Khan Maykr because she is nothing in the mission he pursues. Doom Slayer is not a tool of anyone, but only fighting for the sake of themselves and the survival of mankind. With the help of VEGA and the equipment on the Fortress of Doom, Doom Slayer is determined to find the remaining Deag clergy no matter where they hide or how well Khan Maykr protects them, and carries out the alert. the enemy I always wanted.
Because the hellish priests now hide under Khan Maykr's protection, the Doom Slayer needs to activate the Celestial Locator on the Fortress of Doom to search for them. But first, he needed to find its missing parts and this mission led him to Exultia, then to Hell. The reason that Doom Slayer went to Hell is to meet Valen - the once traitor Argent D'Nur now living in exile in Hell - to power the device he has just found. Valen accepts to help Doom Slayer, and gives him a knife to destroy his son's heart, which controls the Icon of Sin, which Khan Maykr is planning to revive as a new tool.
With the Celestial Locator activated, VEGA finds the second cleric, Deag Ranak, who is hiding in an Arctic UAC base. Here, Deag Ranak is protected by a Doom Hunter, a demon designed to hunt down the Doom Slayer and the Night Sentinel warriors in the past. Following the recommendation of Deag Ranak, this demonic race thought to be extinct because of the events in the 'Unholy Crusade' but actually still exists and has been improved by Earth technology. He believes that Doom Hunter will be able to save his life, but Doom Slayer is willing to make this race extinct again before forcing Deag Ranak to accept his fate.
Deag Ranak's death forced Khan Maykr to hide the last missionary Deag Grav in a secret place and speed up the invasion of the Earth. This forced Doom Slayer to change tactics and attack Super Gore Nest in Europe, where the density of demons is most dense on Earth to delay the invasion. The Doom Slayer successfully destroyed the Super Gore Nest but this did not help the search for Deag Grav, so VEGA made an unexpected suggestion: looking for Dr. Samuel Hayden, who might know where he was hiding. .
In order to find Samuel Hayden, Doom Slayer headed to the ARC base where Samuel Hayden was in a "devastated body" because of a failed counterattack operation. A Marauder - the common name of those who used to be comrades of Doom Slayer in the Night Sentinel ranks but has long been corrupt - appeared here to kill Doom Slayer but failed. The Doom Slayer brought Samuel Hayden and the Crucible he was holding to the Fortress of Doom. When he awoke, Samuel told him that Deag Grav was hiding at Sentinel Prime, an ancient city of Argent D'Nur. As a Warrior King of the Night Sentinel, the Doom Slayer can enter the city unobstructed, but first he needs to find his way there.
Finding Sentinel Prime is not easy, but fortunately there is still a gateway to this city located in Hebeth, another ancient city buried deep on the ground of Mars. Instead of starting an archeology and excavation to search for Hebeth, Doom Slayer used the BFG 10000 on the UAC base in Phobos to carve a giant crater on the surface of Mars, causing Hebeth to be exposed outside. He walked across the immense space between Phobos and Mars in a bullet to Hebeth and entered the teleport gate. At Sentinel Prime, he defeated a giant demon called Gladiator, killing Deag Grav even if Night Sentinel's rule did not allow the killing of a missionary on this sacred land and returning to Fortress of Doom.
End the invasion
When he returned to the Fortress of Doom, Khan Maykr tried to sabotage the fortress to prevent Doom Slayer from continuing to disrupt her plans. Because this fort was built by the Argent D'Nur on the help of the Maykr clan, she easily disabled the fort's energy as well as teleport the evil into the control room to kill the Doom Slayer. However, all efforts were futile when the demons were slaughtered and the Crucible sword was able to power an entire planet to be used as a source of power for the Fortress of Doom. Samuel Hayden himself also became the new 'housekeeper' of the fort while VEGA was extracted for a new mission: destroying the Icon of Sin at Urdak.
But first, the Doom Slayer needs to retrieve his Crucible sword, which is embedded in the heart of a Titan lying in Taras Nabad. He only took away the hilt of the sword and left the blade in order to further suppress the Titan from reviving it, then re-cast the new blade to use. At Taras Nabad, the game reveals to the player that Khan Maykr has allied himself with Hell in exchange for Argent energy to prolong life and keep Urdak alive.
After the Doom Slayer restored his Crucible, Samuel Hayden guided him through the Nekravol stronghold - the Argentian energy refinery of Hell - to find the gate to Urdak. In the home town of the Maykr clan, Doom Slayer uses the knife that Valen gives to destroy the heart of Valen's son and free his soul. This also severed Khan Maykr's ability to control Icon of Sin, causing its instincts to rise, pushing the monster toward Earth.
Outraged by his plans being destroyed, Khan Maykr determined to destroy Khan Maykr himself without knowing that the reason he was still alive was just because she was immortal outside Urdak. After killing Khan Maykr, the Doom Slayer chased the Icon of Sin back to Earth, leaving VEGA in Urdak to keep the portal moving from Urdak to Earth open. After a tense battle on Earth, the Doom Slayer once again destroys the Icon of Sin with the Crucible sword, putting an end to the extreme invasion of Hell on Earth.
After this trophy, it seems that people will have a new religion to worship Doom Slayer. While both demons and 'angels' want to destroy the Earth, Doom Slayer - a man who once was a normal person - stood out to accept the responsibility to save humanity. He did it not only once, with not only one race, but not just one universe. Although I believe that Doom Slayer does not care if he is worshiped or not, he will surely be pleased to see that humanity continues to exist. Doom Slayer will definitely not stop Rip & Tear when outside forces threaten the species he was once a member of and still want to protect in the future.