Maybe a dark ritual involving sacrificing a limb to blind someone or something?
Maybe, but I doubt it.
Since every time a new magical element like this is posited, the obvious thing to do is ask how someone like Quirrell could abuse it, I'll note that Canon Voldemort was capable of instantly creating a better-than-new magical prosthetic for Peter Pettigrew after the latter sacrificed his hand for a ritual.
Limb farming his own Death Eaters is thinking too small, particularly since the prosthetics might be identifiable. I'd go with "Imperius innocent civilians into casting the ritual for you and then memory charm them so they don'...
Edit: New thread posted here.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 86. The previous thread has long passed 500 comments.
There is now a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16.
As a reminder, it’s often useful to start your comment by indicating which chapter you are commenting on.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: