by Cruelsader
The game does not scale well. In general, it is much more difficult solo than with two players. The intro scenario is a good example: you start with the forest spider and the road location REGARDLESS of the number of players. You have to overcome the initial threat value alone when questing or your threat rockets and … you know. Also, some of the treachery cards are devastating early: for instance, the spider attachment that does not allow readying without paying. You should feel proud winning the intro with initial (not optimized) decks. :)The Dol Guldur is very hard solo. It is possible to win it with good deck and ton of luck but .... in short, I understand why you are looking for variants. Adding the fourth hero to Dol Guldur in solo is not overpowered. It is a significant boost but it pales in comparison to the boost you get with playing two deck solo (i.e. two player game solo). Try the four hero variant and let us know how it turned out!
P.S. Before switching to solo two-deck play I experimented with variants. I liked the following variant the best because it mitigated risks in the early game when the solo player is most vulnerable without giving much boost later. The variant is simple: you get one resource gathering and card play phase before any random elements of the setup of the quest. That is, read the scenario instructions, put the indicated cards to the staging area etc but do not reveal cards if the scenario so instructs. First, gather three resources and one card, play allies and attachments. You can take actions but but xhausted heroes remain exhausted. Then continue with the setup and start normal play.