Either Ghost Prison or Binding Evil event will always appear in every game.
The Nephalem may occasionally find The Crazed Man sacrificing a human on an altar. If the hero talks to him, The Crazed Man will attack. Upon his death, two Wildwood Bulwarks to the left and right of the altar will awaken. They are much more powerful than normal Bulwarks, and have the green gas cloud sprout attack like Wood Wraiths.