With an average group level of 68ish or below you can get this as a reward out of a standard mission (you know you have the right one because you only get an option of one of them)
Shrouding down works - I did it with 3 65 shrouded down and 1 75. Removed shrouds once the 75 was in instance able to do the mission with the entire group at 75
Took 4 runs through to get it. All loots attunable in the right level instance