Let me start with a disclaimer: I am not asking for tips or decks on how to beat this quest. I have already beat it quite handily with a few different decks (also got a win on my first try).
What I am struggling with, though, is that there aren't so many archetypes that really work against this quest. I really like it and I'd play it more often, but there is such a narrow pool of deck types that can deal with the Balrog's attacks that you really have to tech against the quest to beat it. For instance, I couldn't just pull out, say, a top-tier Ent deck, because it just can't defend six attack round after round; regardless of the deck's power level (a bit like Journey to Rhosgobel).
Essentially, what are different decks/strategies you've employed to take down the Balrog. I can really only think of three (and a half) ways:
Chump swarm (most reliable IMHO)
Tower Defender (incredibly hard)
Frodo (really limits deckbuilding)
and cheese (Nori, Galadriel, threat reduction event recursion)
Are there any solutions to take standard power decks up against Shadow and Flame? Just to give it more replayability.