I played about 5 solo games of Runebound (core only) using the doom track and travel hazards variants, and nothing else. I finally succeeded on my fifth attempt, using Silhouette. Surprisingly, I defeated Margath and another dragon lord before the end game began (4 times out of 5, I made it to the end game then died). Runemaster Baras was a helpful ally in my one victory, as were the following items: charmer flute, staff of light, chain mail armour and belt of strength (and some magic weapons). Of course, luck of the draw from the market deck, and when encounter rewards allow you to draw items from the deck, was a factor in being able to obtain the kinds of items I did in game 5.
Silhouette's ability to score 2 points of damage on ranged attacks, and her ability to attack on two different phases in a round, were also key to the victory (because of the charmer flute, Silhouette's ability to attack twice, Runemaster Baras assisting with rerolls, and a dragon rune that dealt 3 magic damage, I was able to defeat Margath by the start of round 2). I concentrated primarily on boosting Silhouette's ranged and melee attacks when she levelled (she reached level 9 by the time she faced Margath).
Of course, lady luck is very fickle, both with card draws and dice rolls… I wonder how often I'll be able to repeat this feat, especially with other characters (seems to me that it is critical to be able to deal significant damage in the first phase of combat, which most characters are unable to do).
Winning on the "most difficult setting" for a solo setting was tough, and all the more enjoyable and rewarding.
I'm new to Runebound, and loving this game!