Finally beat this dang quest with this puppy. Quest fast and hard, try to get threat reduced any way you can as early as you can while the Power of Mordor deck lets you. Try to get a fifth hero early to help with resources and speed.
In the end game you want a tanked up Imrahil and/or Defender of Cair Andros blocking specifically, Eomer with lots of damage output potential to take out Thane and possibly the nazgul if you draw him, and just a really large board of allies who are buffed up by Faramir each turn to handle all your questing along with Lothiriel. A Desperate Path saved my butt and made for a really huge play.
The best Power of Mordor cards to draw are A. the one that makes you take one threat every time you draw, B. the nazgul, believe it or not. C. the tower that knocks your threat threshold down, prob in that order, imo. Hopefully you won't draw sidequests, but if you do you might have to just deal with them in the staging area. Hopefully you can smack down the right When Revealed effects at the right time. But the thing I realized about this quest finally is, it isnt just the Power of Mordor deck or the tough quest phase Forced Effects at each stage 2b card-- its the particular synergistic combination-of-suck from both together that you wind up having line up to deal with. Some combinations create way worse overall existential catastrophes than others, and you can't prevent either from happening, but what you do have a little bit of control over is the timing they hit. So dont focus too much of your ongoing anxiety/mortal dread on either the Power of Mordor cards OR the Quest Stage, but instead try your best to keep things moving and keep them from lining up lining up. You want to avoid being surprised by situation A and B at the same time.
A Very Good Tale would be nice, because it works well with your high ally count and with Ranger of Cardolan. Replacing Sword-thain with Resourceful would serve the same role while eliminating uniqueness conflicts. In addition, you can play Resourceful turn 1.