[Lostie!]

The 100th episode

Spoiler:

I was expecting someone to die, but Elias and Root in one episode

That shot of the camera panning down to Root's body was chilling.

Having The Machine take on Root's voice is a really nice way to keep Amy Acker a part of the show until the end. Now I assume "Root"'s voiceover with the flashforward to the destroyed subway in the first episode was actually The Machine speaking all along.