If you guys remember correctly in Halo 3 when trying to find the Catch skull on the mission "The Storm", the way to unlock to skull was to kill one of the Wraiths and leave the other one untouched. If you killed one of them the skull would appear, but if you killed them both the skull disappears completely.
I am wondering if there is anything that might change during normal game play by using this old tactic to uncover something.
Basically do a mission DON'T kill enemy vehicles and maybe back track to see if there is any changes or check around the area where vehicles are and see if there are any changes..
Just a thought.
During TLNoS there is a Wraith and by surviving 5 waves of never ending Covey attacks a Drop ship comes down. The occupant quickly disappears, maybe the wraith is connected some how?