Designed specifically to beat Escape from Dol Guldur (final quest of Shadows Fall campaign) on Challenge mode.

Early Game

Look for Round Shield and Ranger Spear to get block on your heroes. Self-Preservation will also help. Erebor Watchman and Westfold Outrider are also helpful to give your heroes a bit of breathing room from Sauron's minions. Get out of the first location as quickly as possible, as you won't be able to withstand the direct damage forever.

Mid Game

Start getting your game pieces in place. You want at least one Guardian of Arnor with a Raiment of War (or Ranger Spear if necessary). Get a weapon on Faramir to help draw the rest of the cards you need. Other attack boost should go on Idraen. Sword that was Broken for Aragorn, so that he can drop 6 per turn. It's also a good idea to get out a Northern Survivor with a Block-granting attachment going into the final location.

Late Game

Hopefully you managed to keep a Forest Snare, as that can help with one of the big uglies at the end. Otherwise, a combination of a souped-up Guardian of Arnor, Imladris Minstrel, and a souped-up Idraen should handle the combat. The questing should come from Aragorn, Northern Survivor, and Helpful Squire. If you can, hold 2x Helpful Squire in your hand for when you trigger the Fate event doubling questing -- done right, you should win in one turn, as Aragorn will contribute 12, a Northern Survivor will contribute 8, and the two Squires 6 each. Total with those four characters will be 32 !