In the book, after the diadem is destroyed by Fiendfyre caused by Crabbe, Hermione mentioned that she had read that this fire could destroy Horcruxes. Still, it was difficult to control. In The Order of Phoenix, Voldemort uses that kind of magic against Dumbledore, but Dumbledore repels it. Also it is mentioned in the book that there are ways to stop it. So, why bother and looking for a sword and not using this spell ? Also why didn't Dumbledore use this spell to destroy the Horcrux, but instead got his hand injured?

Inexperienced casters will be able to conjure the flames but will have virtually no control over the curse once it has been unleashed, thereby making the fire a deadly backfire. More experienced casters, such as Lord Voldemort, may control the flaming beasts they create, even condensing it into a single, colossal animal of their desire. There is also a charm to cease the flames as well as one to disperse them, but unfortunately Vincent Crabbe never paid attention in class long enough to learn it, therefore costing him his life. It is also possible that the fire may eventually burn off on its own, if it is unable to consume enough material to sustain it, and if so, the ash left behind may become Ashwinders.

-From the Harry Potter Wiki article on Fiendfyre

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    Dumbledore got his hand injured, not trying to destroy the horcrux, but because in a moment of emotion he tried to use the horcrux as what it was (a ring) and ignored/forgot the curse that was (as he should have known) attached to the horcrux.
    – gowenfawr
    Commented Aug 18, 2014 at 11:15
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    Voldemort only used Fiendfyre in the movies, not the books. And it was never identified as such, it could have been normal fire. I tend to use the the Harry Potter wiki with caution, given the undue amount of canonicality they lend the movies. Commented Aug 18, 2014 at 13:01
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    I can't think of any canon source that states 1) that Fiendfyre is a "backfire", 2) that Fiendfyre can be formed into an animal of the caster's choice (movie contamination, maybe?), 3) that Fiendfyre will burn off on its own, or that 4) the ash from Fiendfyre can beget Ashwinders. In fact, FBAWTFT says Ashwinders are created from "any fire to which Floo powder has been added." (Yes, I realize Fiendfyre is a type of fire). Granted the Wikia info could all be on Pottermore and I haven't read it yet, but, if not, I'm concerned the Wikia paragraph is incorrect. Please, correct me if I am wrong. Commented Aug 18, 2014 at 14:47
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    @Slytherincess The Wikia wrong? You must be joking. Commented Aug 18, 2014 at 15:55
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    @AnthonyGrist - I know it's hard to accept, but we'll just have to find a way to go on in light of this shocking news! ;) Commented Aug 29, 2014 at 4:43

4 Answers 4


Firstly, there is no mention of Voldemort using Fiendfyre against Dumbledore in Order of the Phoenix.

There are ways to stop it but it is also very dangerous and difficult to control, so probably not worth the risk.

For this same reason, Dumbledore didn't use it to destroy the ring Horcrux, as he already had another means of doing so, the sword. Also, he didn't get his hand injured trying to destroy the Horcrux, but rather because he tried to handle it without taking precautions, as he was impatient to try out the resurrection stone.

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    Voldemort using Fiendfyre was (as usual) a Wikia invention by someone unable to distinguish canon from their own fantasies Commented Aug 18, 2014 at 14:27

Hermione gives her opinion about Fiendfyre in Harry Potter and the Deathly Hallows chapter 31.

Fiendfyre – cursed fire – it's one of the substances that destroy Horcruxes, but I would never, ever have dared to use it, it's so dangerous.

We don't learn the details, but Hermione had certainly researched Fiendfyre and how to stop it, so you have to trust her judgement.


I would speculate that while Fiendfyre can, and did, destroy a Horcrux, it won't always. Fiendfyre is a curse, and is considered "Dark" magic, and it follows that sacrifices would need to be made for it to be maximally effective. I think Fiendfyre needs to be fed an enormous amount of "fuel" to become powerful enough to destroy a Horcrux.

In the case of the Diadem of Ravenclaw, which was destroyed by Fiendfyre in the Room of Requirement, the curse was fueled by a huge amount of valuable, combustible material stored in the room, such as old furniture and other objects.

I bet if the trio had cast the curse in some isolated area in an attempt to destroy the locket, it wouldn't have worked unless they were willing to burn down 100 acres or forest, or otherwise destroy a ton of stuff.

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    Is it ever stated in the books that dark magic needs a sacrifice to be more powerful?
    – fez
    Commented Mar 9, 2023 at 8:47
  • Uhh yeah fez, it's called a Horcrux, ever heard of it?
    – FBB
    Commented Mar 16, 2023 at 21:01
  • "Fiendfyre is a curse [...] sacrifices would need to be made for it to be maximally effective" - What is the source for your claim?
    – fez
    Commented Mar 17, 2023 at 6:40
  • The part in the book where they burn down the whole room of requirement and it destroys a Horcrux. I'm sure fez you're not suggesting that the Anti-Voldemort team was so incompetent that they simply overlooked the fact that a well-known, if seldom used, spell could easily destroy the locket. Certainly, such a sweeping claim would need a source.
    – FBB
    Commented Mar 31, 2023 at 18:11

Fiendfyre does not destroy the Horcrux. It is stabbed with a Basilisk fang, then Ron kicks it into the fiendfyre.

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    Are you sure you aren't getting mixed up with the other Horcrux which was stabbed with a Basilisk fang?
    – Rand al'Thor
    Commented Oct 22, 2016 at 16:44

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