Voldemort used horcruxes, obviously (that's what the five hidden items in the elemental pattern are)
I would hesitate to call this "obviously". Certainly, there's the Pioneer plaque, but as for the elemental pattern, all we actually have is Quirrell remarking on the fact that Harry's ideas have an elemental pattern, and Harry himself failing to realise it. There's nary a hint that Harry's guesses correspond to anything that actually happened.
New chapter!
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 102.
There is 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.)
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: