At the end of As Diablo I draws to a conclusion, the hero defeats [[Diablo]], and takes Diablo's [[Soulstone]] within his own body, intending to contain Diablo there forever. Doesn't work to well for him- which had potentially unforseen consequences. According to [[Deckard Cain's Journal]] it takes about 2 days for the spirit of Diablo to corrupt and posses him. At which point , he became the Dark Wanderer fully possesed and left [[Tristram]]. Immediately after his departure, hordes of demons either killed almost everyone thereor possessed the remaining denizens with the exception of Deckard Cain whom was only captured. It is implied that the Dark Wanderer is directly responsible for that carnage, although it may have just been a side-effect of his presence.