Nephi refers to a mist of darkness and the vapor of darkness (v. 5). He is seeing the actual vapor of darkness that covered the land of promise for 3 days after the death of the Savior (3 Nephi 8:19-23). However, the mist of darkness also symbolizes the temptations of the devil which had overcome the Nephites right before their destruction. This was a time of incredible wickedness among the people, six years had not passed away since the more part of the people had turned from their righteousness like the dog to his vomit, or like the sow to his wallowing in the mire…their hearts were turned from the Lord their God, and they did stone the prophets and did cast them out from among them (3 Nephi 7:8,14).