This quest was annoyingly difficult. In one play, I drew 3 Athelas as shadow cards in a row...
I tried this quest with Legolas to fight the numerous ranged enemies in the quest, but it just didn't cut it. Would frequently just die to all the treacheries. Then I tried an all Lore deck, and continued to die to treacheries - and somehow wasn't even drawing enough to find the Lores. So what did it was to slot Eleanor in to stop the treacheries, and take advantage of the new Spirit draw card in this pack, Ancient Mathom, which is FAR better than Lorien's Wealth.
Deck strategy is to just draw as much as possible to find the 3x lore of Imladris, while hopefully also having an Athelas objective by the end. Peek into the future with Henamarth to see if there is a nasty treachery coming up, and to know exactly how much to swing for in the quest. You want to get right up to 1 or 2 progress away from 3A so that you can end the quest as soon as you can heal Wilyador up. Protector of Lorien helps with this - since you will have so many cards in hand, you can chuck the ones you don't need away from a Willpower boost.
It's important to get Song of Kings onto a Lore character ASAP, so that you can put Steward of Gondor onto that character for resource acceleration. You have to Steward onto a Lore character so that you can afford 2-3 Lore of Imladris onto Wilyador. You want to end this quest as quickly as possible since there is a time limit on Wilyador's HP. Keep a Sneak Attack + Gandalf at the ready to take care of Hummerhorns, because if it engages you, it's a guaranteed kill on one of your heroes, which you don't want. Otherwise, use Gandalf for card draw if you haven't found your Lore yet. Also, get Radagast out as soon as possible so that he can contribute to healing Wilyador. I ended up not needing most of the cards in my deck, since there is a clear line of cards that you need to play to beat the quest.