Why are inferi so dangerous to wizards?

Question

Inferi are mentioned in Harry Potter and the Half-Blood Prince (where we also see them) and later in the Deathly Hallows as the bodies of dead people raised by a dark wizard. There seems to be a wide-spread fear of them, but why?

Except the natural horror that one will experience when seeing a dead body walking, they seem to be pretty harmless. Actually an armed muggle will be much more dangerous than an inferius that is quite slow and has only its bare hands to fight with.

I understand that they are immune to certain spells like Avada Kedavra, Crucio or Imperius but in general there are lots of spells that can be used against them. They can be burned, frozen, pushed back, or just transfigured into something harmless.

So why?

Answer 1

As warriors of evil, Inferi do indeed seem to be relatively easy to tackle singly:

‘Petrificus Totalus!’ yelled Harry, struggling to cling on to the smooth, soaked surface of the island as he pointed his wand at the Inferius that had his arm: it released him, falling backwards into the water with a splash. - _{^{HP and the Half-Blood Prince}}

However, when they come, they tend to arrive in large packs. And since they're essentially indestructible, that makes them pretty formidable against all but the most powerful of wizards:

He scrambled to his feet; but many more Inferi were already climbing on to the rock, their bony hands clawing at its slippery surface, their blank, frosted eyes upon him, trailing waterlogged rags, sunken faces leering.

Answer 2

Somehow it seems the most important thing has gone unmentioned:

Pro: Upkeep

1. Lock up 50 mind-controlled muggles in one cave and lock up 50 inferi in another cave.
2. Keep locked up for 20 years
3. Return to inspect results.

I am pretty sure you will find your 50 inferi up and running, but your 50 muggles will be positively a stack of useless bones. And as magic can't create food¹ your best option is to just use defenses that do not require upkeep.

But there are other considerations as well:

Draw: The fear factor

As mentioned by others already resurrecting someone you personally knew as an inferi is definitely not a nice experience. There are two important things here though:

• Inferi look so little like their former self that you are likely not to even recognize them
• And even if you recognize them you will just be more motivated to put them out of their misery rather than less.

And on top of that all uses we have seen of inferi were impersonal, so it seems the psychological attack vector was not really considered by the dark mage world. All that however does not mean that it doesn't creep anyone out when a half-dead monster appears, or that one wouldn't be extremely afraid of being turned into a half dead monster when fighting Voldemort.

Con: Fighting power

1. Throw 50 mind controlled muggles that can not feel pain and 50 inferi in an arena
2. Watch the free for all
3. Observe last man standing

As long as we didn't tamper too much with the minds of the muggles (just so they don't feel pain and are determined till the end) I think it's a fair assessment that the muggles will easily win. Traditionally zombies have two strengths:

• Numbers
• A single scratch is enough

Both things do not apply in such a scenario, so the muggles would have to mess up badly to lose. If they wouldn't be mind controlled then they might have a bit of a harder time, but in the end you would need to mind control them either way if you wish to use them as your long-term loyal guards.

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Conclusion

In conclusion I think it's fair to say that the reason they were used was not because of their strength against wizards, but the fact that they could stay there for a hundred years and still be ready to fight.

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¹ Well, there are ways around that (multiplication, enlargement, etc.), but lets just go with the standard story telling version.

Answer 3

Have you never seen The Walking Dead?

In all seriousness though, as you mention in the question, there is going to be quite a shock factor associated with seeing a dead body walking towards you. Especially if (lets just play a little bit here) it's the now dead body of your next door neighbor that Voldemort, or one of his death eaters, has just killed, reanimated, and set on you.

Additionally, there are many spells that have little to no affect on inferi. You mention Avada Kedavra, Crucio, and Imperio, but also take this snippet from Half-Blood Prince:

A few of the stumbled, one or two of them bound in ropes, but those climbing onto the rock behind them merely stepped over or on the fallen bodies. Still slashing at the air with his wand, Harry yelled, "Sectumsempra! SECTUMSEMPRA!"

But though gashes appeared in their sodden rags and their icy skin, they had no blood to spill: They walked on, unfeeling, their shrunken hands outstretched toward him...

Harry Potter and the Half-Blood Prince, Pages 575-576

Add onto it that, as Richard said previously, you are more likely to be attacked by a group of inferi than just a single inferius. Get attacked by many inferi at once and you have yourself a pretty scary situation. Not to mention the fact that it takes a powerful dark wizard to reanimate a dead body, and that he/she could be lingering around in the vicinity as well. All in all it would be enough to scare just about anyone, muggle and wizard alike.

Answer 4

Contrast how Harry fought the Inferi with how Dumbledore fought when the latter came about.

Harry panicked and clearly forgotten what Dumbledore told him within the hour while they were crossing the lake (although given the situation, it was quite understandable). Dumbledore was able to protect them with one spell, probably due to his experience and him staying calm

The fear is a big factor, along with experience. Given that a lot of wizards don't know how to cast a Shielding charm (page 115 of HBP), I suspect few have ever fought an Inferi or have ever dueled at all. The inexperience combined with the natural horror can do wonders to the general population.

Also, the ability to cause pain can be a deterrent for muggles. You don't actually have to disable them in combat; you only need to inflict enough pain. In contrast, you have to physically disable an Inferi to stop them from harming you.

Answer 5

Most people don't fight. They're not used to fighting. They've never thought about using most of their spells to defend themselves in a fight. And the few spells they did learn for fighting were long, long ago. And thanks to the quality of DADA, they didn't even learn those very well at the time.

This is amplified by the fact that walking dead are rather horrific things.

Just imagine, you're out hiking in the woods, carrying your trusty cell phone.

And you run into three zombies!

The main thing on your mind is "THE DEAD ARE WALKING!" You panic and tremble and run, but you get backed into a corner. You eventually remember that you have an app for that. But you never use it. You're too panicked to search your memories to remember when you've seen it before. You're shaking and trembling and are barely able to fumble through your menus.

And you get your brains eaten long before you manage to pull up the app that would have saved you.

Answer 6

My reading of the books is that wizards, like Muggles, have a natural feeling of revulsion at the idea of re-animated corpses. Unlike Muggles, wizards have the means to defend themselves against mundane attack, although the points about fear factor and numbers are somewhat valid.

Moreover, you have hit on what I feel is the single biggest weakness of Potterverse. Wizards in the Potter universe seem to be capable of tremendous feats of magic, but also sometimes quite bumbling. Adult wizards should be far more capable than Rowling gives them credit for, but Potterverse is her playground and she is such a compelling storyteller that she gets a pass for it.

Answer 7

I think fear is the biggest reason, I mean imagine that Voldemort killed your best friend (+made her/him a zombie) and set him/her on you. You wouldn't want to hurt him/her but they totally want to hurt you. Zombies are naturally frightening so you would naturally be scared. It's human instinct!

Plus they are indestructible as stated in The Half Blood Prince:

A few of them stumbled, one or two of them bound in ropes, but those climbing onto the rock behind them merely stepped over or on the fallen bodies. Still slashing at the air with his wand, Harry yelled, "Sectumsempra! SECTUMSEMPRA!" But though gashes appeared in their sodden rags and their icy skin, they had no blood to spill: They walked on, unfeeling, their shrunken hands outstretched toward him...