I've beaten this quest solo, but we are having severe problems with it in 3- and 4-player. A good option seems to be that we quest moderately in the first stage so we do not progress until we have massed an army of allies, but by the time we decide to progress, Gondor almost always threats out (he runs straight combat, and his starting threat is always 32-34). Dwarves and Spirit/Tactics Rohan can usually hold its own, but we can't seem to both manage threat and survive combat. Which is weird, because I've taken on the four trolls solo and won with a Lore/Spirit deck (although granted, Loragorn and Spirfindel played a part in that).
Can you share any good strategies? We're currently playing through the quests in release order and struggling with this scenario. Maybe we're just unlucky, or one more player needs to go for healing or threat reduction.