The trailer. You'd think the Diablo universe was out of demons after three games of Demon Slaying, but no, Lilith, Mephisto's daughter, is still alive and kicking. The summoning ritual is performed by three "cultists" who are sacrificed and their blood flows into the air to weave a cloak for Lilith, as the last "cultist" gets nightmarish glimpses of the demon's home dimension. All accompanied by a soundtrack that is the cross between Infernal Choir, One-Woman Wail and Drone of Dread. After completing the campaign for IV, you then realise that the three were not cultists, but adventurers/mercenaries tricked by Elias into joining him.
Continuing from III, even after decades have passed, Alcarnus is still a place of depravity. This time, it's become the laboratory of a deranged Necromancer researching immortality.
To learn how Elias became immortal, the player climbs into a coffin on a reef. The coffin shuts and then slides into the water and sinks. This wouldn't be so bad, except you can hear your character's panicked breathing then choking as water quickly fills the coffin and seemingly drowns them. A similar situation occurs as the end of the quest, where water begins to rise as you make a mad dash to escape, only to inevitably drown.
The Season of Blood update added a postgame questline where an elderly priest offers to help cleanse Lilith's blood from you. After procuring the necessary materials and meeting him at the exorcism site, he begins the ritual, but something goes horribly wrong. A rain of blood, the same rain of blood that fell during the Sacking of Caldeum, suddenly begins falling despite the ritual happening not only indoors, but within Inarius' former seat of power. Then your character suddenly begins vomiting blood petals before blacking out. When you come to, the knights who were in the chamber with you all lie dead, blood covering the chamber, with the priest the only survivor as he desperately begs you to just leave. Lilith may be gone, but her mark on you still remains...
The village of Qara Yisu in the Dry Steppes was originally beset on all sides by bandits, cannibals and monstrous wildlife. Then, one day, a dark voice suddenly came from the village's salt mine, offering to grant the villagers the strength they needed to survive. This Deal with the Devil went about as well as you'd expect; the voice was in fact a Demon who proceeded to curse the villagers, transforming them into its demonic slaves and forcing them to kill anyone who ventures too close to the ruined village. The worst part is that the transformed villagers are painfully aware of their cursed existence, desperately begging you to run even as they are forced to attack you.
And the demon responsible for this madness? A Fallen. Fallen are arguably the weakest type of demon in the setting, and yet this one was able to unleash such horrors on countless innocent people.
