The Abomination Vault is the official Darksiders novel written by A. Marmell. My newest Darksiders fanfiction story, Death’s Blessing, picks up immediately after it and leans quite heavily on some details of its plot, so I made this summary to aid the readers who either never read the novel or don’t remember it well. Beware of spoilers!
The novel takes place long before the games of the main series (but long after Genesis), following five hundred years of Death’s unexplained absence. In it, he and War pursue an outcast angel, Hadrimon, and a rebellious maker, Belisatra, who teamed up to excavate and activate an arsenal of ancient Nephilim weapons called the Grand Abominations (GA). These weapons, conceived by Death ages ago, before he became one of the Horsemen, are part mechanical and part organic, made from the biological remains of the Ravaiim, the first race the Nephilim exterminated in their crusade against Creation. While the GA aren’t exactly sentient, they appear to posses a rudimentary, malevolent consciousness and some telepathic abilities that allow them to communicate among themselves and with their wielders. They are vastly more powerful than any other weapons in the Darksiders universe, but also evil, treacherous and full of hate. Too dangerous even for the Nephilim to use, they were locked up in a hidden pocket dimension – the Abomination Vault.
However, some were lost on ancient battlefields before the Vault was established, and Hadrimon managed to find at least one of them before the events of the novel: Black Mercy, a pistol with the power to kill with any shot that wounds the target. Once Death realizes the gravity of the threat, he informs the Council and the other Horsemen and is tasked with stopping Hadrimon and Belisatra from reaching the Vault. However, he vehemently refuses the help of his brethren, hoping to hide his own personal connection to the GA and the Abomination Vault, which can be accessed from a portal in his home. When Strife challenges this suspect decision, they almost come to blows. War chooses to follow Death regardless, and eventually joins him on the quest.
A special substance is needed to activate the full potential of the GA: Ravaiim blood. Hadrimon and Belisatra learn this directly from Death’s unguarded mind when he touches another GA, Mortis (which makes an appearance in Darksiders II). They travel to the Ravaiim homeworld and mount an impressive expedition to extract the blood from the grounds that soaked it millennia ago. Death and War, with the help of the angel Azrael, dismantle the operation. To make sure no one can ever make a similar attempt again, Death employs his necromantic magics to gather all the leftover Ravaiim blood from the entire world and put it in a jar that he plans to destroy. Afraid that the enemy will see through his plan, he also prepares two fake jars: one for Azrael and one for War – and tells everyone involved that War will be carrying the real one.
Hadrimon pursues War, kills him with Black Mercy and takes off with the fake jar: an outcome which Death fully expected. After disposing of the real jar, he manages to revive War by stabbing himself with the Chaoseater to empower its connection with War’s soul, which still clings to it. But he never admits that he lied.
They take some time off to rest and recuperate, and then proceed to confront the enemy in a battle waged at the very entrance to the Abomination Vault. In addition to Belisatra’s constructs and Azrael’s angels, a band of demon mercenaries led by Raciel, a fallen angel that used to be Hadrimon’s lover, joins the fray. Azrael uses illusion magics to take her appearance and distract Hadrimon, which results in his death. Belisatra is captured. In the end, Death seals the Vault again.