Used to beat Siege of Cair Andros from Heirs of Numenor two-handed, along with a lore deck (https://ringsdb.com/decklist/view/11378/siege-of-cair-andros-lore-1.0)
This deck was using progression cards from one core set, the Shadows over Mirkwood cycle, the Dwarrowdelf cycle, and the Heirs of Numenor expansion. I used two mono-sphere decks for this quest due to The Master's Malice punishing multi-sphere decks. I aimed to clear The Banks and The Citadel, removing quest cards 2 and 4. This allowed me to remove Quest card 2B, which I viewed as the most dangerous for the deck, while turning Quest card 5B into a battle instead of a siege.
Most of the 1 and 2 drop allies are used as chump blockers, especially if Horn of Gondor has been drawn. I tried not to block with heroes without shadow cancellation, so Beregond was used for questing when possible. Enemy archery cards were very helpful for pumping up Gimli -- the encounter deck doesn't contain any surprise damage, so keeping him one HP from dead was fine as long as I wasn't blocking with him.
Gandalf was used exclusively for threat reduction. Once The Banks and The Citadel are cleared, this deck brings a lot of attack and defense to quickly quest through both battle and siege stages. However, it brings almost no willpower without Gandalf, so Quest Card 2B can be extremely difficult.