Expelliarmus and backfiring

[Sandy]

No: HPFGUIDX 184562

--- In HPforGrownups at yahoogroups.com, "happyjoeysmiley" 
<happyjoeysmiley at ...> wrote:
>
> Okay, I'm sorry if this has already been discussed.
> 
> When Voldy used the AK curse when Harry was a baby, it backfired - 
> okay, Lily's sacrifice acted as an invisible shield and repelled 
the 
> curse, I guess. Fine.
> 
> When Voldy used the AK curse in DH climax, Lily's protection was 
not 
> with Harry. Harry is the master of the Elder Wand and so the curse 
did 
> not kill him. OK. Now, Expelliarmus spell only disarms the 
opponent. 
> So, how did the AK curse *backfire* on Voldy? I think backfiring 
would 
> have made sense had Harry used Protego. Not sure how Expelliarmus 
> would help with respect to backfiring.
> 
> Any thoughts / quotes from canon?
> 
> Cheers,
> ~Joey, who always smiles to herself whenever she thinks that JKR 
made 
> it a point that Harry learnt the Expelliarmus spell from *Snape* :)
>

Joey, 

What a fun question.

The master of the Elder Wand is as stated in canon the 'master of 
death'. The closest thing we have to canon in terms of what this 
means is the outcome of the Dumbledore/Grindelwald duel.  Dumbledore 
didn't kill Grindelwald. Besides the love angle, I believe that if 
he had gone after Grindelwald with the intent to kill, the logic of 
JKR's universe says he would have died instead.
   
It seems to me, that what 'master of death' means is that the master 
of the wand can't be intentionally physically harmed in a manner 
that might kill him or her in combat (which means it doesn't have to 
be AK) and any spell used with that intent would rebound on the 
caster. Or in other words the elder wand is like a bullet proof vest 
from which the bullets into the shooter.

So, say you used Serpentsortia, and ordered the snake to attack the 
elder wand master with the intent to kill him; well the snake would 
attack you instead. If you try to drop a safe (or a house as I once 
saw in a fanfic) on the master with the intent to kill the master, 
then the safe or house would drop on you instead.  

You might be able to block this effect with most spells or avoid it, 
but an AK as shown by JKR in canon can't be shielded against. I.e 
Protego doesn't work against it. Only interposed physical objects 
can stop it, i.e. statues etc.  

Using this logic, if Harry had tried to kill Malfoy instead of 
disarm him, he never would have become the master and in fact would 
have died (leaving aside the Horcrux bit in him). Also, note how 
Grindelwald attained the wand: guile, and the manner in which Draco 
obtained it. If he had in fact, attempted to kill Dumbledore, then 
his curse would have rebounded. 

Snape could kill Dumbledore, only because Dumbledore was no longer 
the master of the wand at that point (Draco was), but I think even 
if he had been, Snape may have still been able to kill with an AK, 
if his intent had been to show mercy. 

Although, since an AK has to be used with intent to harm and with 
hate, I'm not sure it can be used for mercy. Snape might have had to 
use another spell to kill Dumbledore if DD had still been the master 
of the wand (or stunned him off the roof or something else 
instead).          

This doesn't mean that a master of the wand has never been killed in 
combat while they were the master, just that any such killings were 
accidental. Say, a tripping spell badly aimed at the master that 
misses and instead knocks a vase onto his head and shatters his 
skull, or one that unintentionally knocks the master over a ledge. 
Since a tripping hex is not used to kill, and assuming the hit on 
the vase wasn't planned as a 'killing attempt', then the master 
could be killed in this way. 

If it was an attempt to kill, then the tripping hex would rebound on 
the caster. It's open as to whether they just suffer the spell 
effects (death in the case of the AK), or are killed by the elder 
wand, in retaliation for the attempt to kill its master. 

In fact, in the right circumstances it might be possible for a 
bumbling muggle to temporarily become master of the wand. Say, if 
Dudley ever accidentally disarmed Harry.  

~ DA Jones