The Darkhallow is the most powerful necromantic rite known. The rite was first created by the necromancer Heinrich Kemmler, one of the most feared and infamous of all dark wizards. The rite is in essence a rite of ascension from mortality to godhood.
It is necessary that the necromancer performing the rite summons as many spirits as possible in order to devour them for the spell gain a greater level of power—godlike power. 
The rite creates a vortex that draws in all life, among other energies, within about an area within a mile. The Necromancer forms all that energy into a big Circle, getting it moving around into a giant funnel and into the one who is trying to consume it—like trying to take in a tornado.
The Heirs of KemmlerEdit
- Main article: Heirs of Kemmler
Kemmler's Heirs intend to call up ancients spirits using the Erlking and then devour them for power on Halloween Night during the powerful Darkhallow spell that will turn one of them into a god-like being with ungodly powers.
In the seriesEdit
- Main article: Dead Beat
In Dead Beat, Harry learns from Mab that the Heirs of Kemmler are seeking the book Die Lied der Erlking to summon the Erlking in order to devour the powerful long-dead hunter spirits which accompany him on his Wild Hunt that Holloween night, thereby perfoming a Darkhallow spell the gain godlike powers.To prepare the way, the Heirs of Kemmler create fear and havoc and helplessness through the city by making a blackout. To get Shiela to recite the Erlking's book for him, Harry explains why the Heirs want to call him up. He explains that they need to call up many ancient spirits to consume them to gain godlike power. She knows right away that he's talking about a "Rite of Ascension"—the Darkhallow. Harry told Kumori he's going to stop them from doing the Darkhallow. Harry asks Cowl how he is going to perform the Darkhallow without the Word; Cowl just laughs, walking away into a rift. It's now necessary for Harry to find the Word himself because he has no idea what's supposed to happen during one and he has to stop it. So he and Butters set out to find it. Harry explains to Butters about the Darkhallow and asks his help beating the drum for Sue, the T-Rex he plans to reanimate to stop the Heirs of Kemmler and the Darkhallow. When Harry and Butters arrive at the scene, they see the vortex forming. With Anastasia Luccio, Donald Morgan and the rest of the Wardens wounded or killed, Harry and Carlos Ramirez head into the vortex to get the bad guys and stop the Darkhallow.
- Main article: Ghost Story
- Main article: Changes
- Main article: Cold Days
In Cold Days, Bob informs Harry Dresden that Halloween night is the only time that the Darkhallow might turn a wizard into an immortal. This is because Halloween night is the only time of the year when the "locked stasis of immortality becomes malleable" and new power can be fed into the mantles of immortality. Halloween is also the only time they are vulnerable to being killed.
Corpsetaker: "Give me the book, give me the Word. Stand with me at the Darkhallow. In exchange I will grant you autonomy and the principality of your choice when the new order arises."
MAB: "Kemmler was a madman, A monster. But brilliant. He learned how to bind to his will not only dead flesh, but shades—to rend them asunder and devour them to feed his own power. It was the secret of the strength that allowed him to defy all the White Council together."
HARRY: "The heirs want to call up the ancient spirits. And then devour them for power."
MAB: Kemmler himself attempted it, but the Council struck him down before he could finish." 
MAB: Should an Heir complete the rite "The heir would gain power such as has not been wielded by mortal hands in the memory of your race."
HARRY: "The Darkhallow. That's what it is. A ritual, tomorrow night. Halloween. They all want to be the one to make themselves into a junior-league god."
MAB: "Power is sweet, is it not?"
HARRY: "Can they do it without the Word?"
MAB: "If they could, why would they seek it so desperately?" 
Harry to Grevane: Corpsetaker sounded all hot and bothered about this Darkhallow thing you guys have planned.", Harry: "I'm sure that you psychotic necro-wannabes with delusions of godhood are all about sharing with your fellow maniacs." 
Harry to Shiela—why call up Erlking: "They're going to use his presence on Halloween night to call up an extra-large helping of ancient spirits in order to give themselve a Valhala sized portion of supernatural power."
Shiela:"Rite of Ascension"—the Darkhallow.
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Dead Beat, ch. 21
- ↑ 2.0 2.1 2.2 Dead Beat, ch. 28
- ↑ 3.0 3.1 3.2 Dead Beat, ch. 38
- ↑ 4.0 4.1 4.2 Cold Days, ch. 11
- ↑ 5.0 5.1 Dead Beat, ch. 23
- ↑ Dead Beat, ch. 29
- ↑ Dead Beat, ch. 34
- ↑ Dead Beat, ch. 35
- ↑ Dead Beat, ch. 39
- ↑ Dead Beat, ch. 41–42
- ↑ Ghost Story, ch. 46
- ↑ Changes, ch. 30
- ↑ Dead Beat, ch. 17
- ↑ Dead Beat, ch. 20