This deck can get rid of some of the nastier locations and enemies without having to travel to them or fight them. If you start out with a good hand and have other players to take care of what the encounter deck does throw at you, you can spend the entire game questing with all your heroes and spending cash like it's going out of style.
Some quests will utterly counter you, of course - anything with a lot of victory points on cards already you can't pick out to get rid of; as well as unique enemies or locations. In addition, too much Doomed might take you out of Secrecy before you can get out your best cards, and without any Spirit, you'll have a hard time getting back down there, at which point you'll be engaged by an enemy and Rossiel won't be able to quest since she'll likely be defending.
When the card support comes out, you could even go so far as to drop Pippin for a longer time of Secrecy and the ability to double up on Rossiel's abilities, but until then, this can be playable with the right quests and other players.