tldr explanation of "pre-sacrifice" and "post-sacrifice": In old prevent lore, Oliver summoned a demon that possessed everyone and blah blah blah. scrapped. Now? Oliver willingly sacrificed himself to give his body as a vessel to a demon he'd made a deal with. He essentially wanted to take a back seat and watch everything without having to make decisions consciously and what not, but of course, demons are dubious things. SO . yeag.