|“||I've seen beyond the veil of this world, oh, mighty Satan. I know there are powers more vast and cosmic than a single vainglorious fallen angel. I speak of the eldritch terrors, Lord Lucifer. Older than the oldest gods.||”|
— Father Blackwood to Lucifer[src]
The Eldritch Terrors are eight ancient inhuman, immortal, and world-destroying entities that predate time and space: The Darkness, The Uninvited, The Weird, The Perverse, The Cosmic, The Returned, The Endless, and lastly The Void. According to the Dark Lord, the eldritch terrors are unkillable and horror incarnate. The idea of horror with enough power to tear through all the realms.
Vision of the Future
Harvey gets a tarot reading from a fortune-teller who shows him a possible future. In his vision, Harvey has received an invitation to a summer internship in Rhode Island. He doesn't want to leave Roz behind, but she pushes him to attend. In his quarters at the Arkham Colony for the Arts, he is greeted by his roommate Howard. Harvey finds demonically-inspired paintings including one of the Dark Lord. When Harvey asks about them, Howard claims that he is visited by "Harbingers of the Void" and that his closet is a portal to the Demonic Underworld. He warns Harvey that the demons are planning to emerge. By painting them, Howard thought he could bind them. That night, a frightened Harvey watches as Howard paints while a blue light emerges from his closet. The following morning, Harvey awakens to find Howard hanging. Harvey opens the closet and only sees clothes. As he prepares to leave that night, he finds that the closet is a portal to the Underworld.
Finding the Old Gods
Prudence and Ambrose track Father Blackwood to the shores of Loch Ness, in Scotland. Unaware of them, Faustus calls upon the Watery Guardians of the West to rise. A creature known only as the Deep One rises from the water and gives Faustus some kind of large, transparent egg. As payment, Faustus offers the creature two sacrifices. Prudence charges Faustus with a sword. Faustus kills the Deep One before turning his attention to Prudence. Ambrose grabs the egg and threatens to destroy it. Faustus begs him not to. He’s spent 15 years inside a temporal church of his own making, purifying himself to wield magicks they couldn’t possibly fathom. While it’s been 15 years for him, it’s only been a month for Ambrose and Prudence. With the Dark Lord dethroned and the pits of the Abyss unmanned, the Old Ones are returning to reclaim the Earth, and then the Eldritch Terrors, Blackwood claims. He lowers his guard and pleads with Ambrose to return the egg. This provides Prudence with the opportunity to knock him out from behind.
The Spellmans and Prudence traps Faustus in the dungeons of the Academy, where he's used to contain Lucifer. Inside his own mind, Faustus takes the opportunity to renounce the Dark Lord, claiming he had found the Old Gods. Lucifer is enraged, asking if by "old gods" he means the pagan monsters who believe themselves deities. But Faustus replies that he means the Eldritch Terrors, older than Lucifer and the gods themselves. And they are coming to claim the Earth.
Summoning the Eldritch Terrors
In the Greendale woods, under the starry abyss of night, Faustus performs a ritual in the woods with Judas, Judith, and Agatha after retrieving his Time Egg from the Spellman household. He calls upon the Eldritch Terrors in the name of the Void. He is their vessel and their priest. He stabs into the Egg with a dagger, and they are deafened by an ear-piercing shriek, falling to the ground in pain. By the time they get back to their feet, the creature inside the egg is long gone. Agatha questions what have they birthed. Faustus replies "The beginning of the end, Agatha. The end of the Spellmans. The end of all things."
The Arrival of the Eldritch Terrors
One by one, the Eldritch Terrors arrive in Greendale, starting with the Darkness which absorbs the light from the town to create despair in absolute darkness through spectral avatars. Then it's the turn of the Uninvited that tears the hearts from the chests of the inhospitable, and of the Weird, a parasite that merges their consciousness with Sabrina Spellman to subdue the town and the world with the intent to make them nourishment for the Void. Father Blackwood, then, uses the Imp of the Perverse to warp reality and create a perverted world in which he is Emperor of a dull and dictatorial world. All of them are defeated by Sabrina and her allies.
The Cosmic takes advantage of the time distortions caused by Sabrina Morningstar's time paradox nature to cause Earth and Hell to collide, causing Heaven to meddle in their business and forcing the two to make a harsh decision; one of them must die. The Sabrinas, however, came up with a different plan, and Nick and Ambrose sent Morningstar to a Parallel Universe. All of this cosmic imbalance affects the veil between the world of the living and the world of the dead, and the Returned unleashes Lazarus and other dead in Greendale, including Edward Spellman and Mrs. Kosgrove. The dead join the living, unaware and susceptible to their defunct nature. Mambo Marie, whose true identity is Baron Samedi, restores order with a little help from Lilith, who stabs Lazarus with the Spear of Longinus.
Meanwhile, Sabrina Morningstar is trapped in a Rogue Cosmos she was sent to to avoid the collision of dimensions. There, she's victim of the Endless, an eternal creature acting on behalf of the Void in a time loop manifesting itself as a sitcom set whose actors are turned into food. After Morningstar returns to the Mortal Realm to warn her twin of the looming threat before dying, Sabrina Spellman uses Pandora's Box to trap the previously defeated Terrors and face the Void. Tainted by it, Sabrina makes the ultimate sacrifice to save her loved ones, and bleeds to death at the Mountains of Madness.
- "Chapter Twenty-One: The Hellbound Heart" (mentioned)
- "Chapter Twenty-Two: Drag Me to Hell" (mentioned)
- "Chapter Twenty-Three: Heavy is the Crown" (mentioned)
- "Chapter Twenty-Eight: Sabrina Is Legend"
- "Chapter Twenty-Nine: The Eldritch Dark"
- "Chapter Thirty: The Uninvited"
- "Chapter Thirty-One: The Weird One"
- "Chapter Thirty-Two: The Imp of the Perverse"
- "Chapter Thirty-Three: Deus Ex Machina"
- "Chapter Thirty-Four: The Returned"
- "Chapter Thirty-Five: The Endless"
- "Chapter Thirty-Six: At the Mountains of Madness"
- The Eldritch Terrors are inspired by the Cosmic horror genre, mostly from the "Great Old Ones" written by H.P. Lovecraft in his Cthulhu mythos.