by Nightrain
Looks like the scenario you're playing is Seventh Level, let me share some of my experiences of beating it solo, at least 65% of it with several decks. I don't think it's a level 3 difficulty too, probably 6 or 7, and Into The Pit is somewhat easier for me. The trick of this scenario is to survive the first 3-4 turns and after that, usually it'll be much easierTry new Glorfindel (very low threat, best hero for me!), Bilbo, Frodo, you can also replace Frodo with Theodred, but sometimes Frodo has the chance to survive in the early turn because you can absorb damage with threat, and your starting threat is pretty low. Marzabul goes to Bilbo
Make use of 3x Elrond's Council, 3x Galadhrin Greeting to reduce threat, sometimes Gandalf can also reduce threat or just killed enemy in the staging area. If you're using Theodred, make sure you have Snowbourn Scout to add progress to location and also act as a shield for your hero in the early turn. Fresh Tracks are also handy
If you survive the first 4 turns, you'll have 4 more cards because of Bilbo draws. Hopefully you have Henamarth to peek encounter, Northern Tracker is useful to add progress to staging, Miner of The Iron Hills to discard Watchful Eyes, 2x Forest Snare to trap enemies, Asfaloth for Glorfindel to add progress, Longbeard Orc Slayer is very nice because mostly Orcs here, and you can Sneak/Longbeard occasionally to deal a lot of damage to them.
The beauty of 3 spheres is that you can utilize all best cards in the game. So, 2x SoG and UC are essential. Bilbo can be a great defender too, attach him Burning Brand and Dunedain Warning, and if you have Arwen ready, he can block up to 5 damages, or with PoL, you can block 8 damages. but again, this scenario felt very fast and aggressive, so you need to survive the first 4 turns, after that, it should be easier.
If you have SoG, mostly attach it to Glorfindel, because Theodred can add his own pool while questing, and I usually have Song of Wisdom in the deck, aside from a backup if Bilbo is accidentally killed, you can also play expensive green such as Gildor, FS, Haldir. Don't forget to have Rivendell Minstrel, a good quester and also help you look for a song.
Hopefully it helps, I'll play this scenario again to see if I can come up with some ideas