Also, if you got the promo characters I wouldn't use the Black Widow in the 2-player game. The rest of the characters should all be just fine though.
Master of Shadows is more broken than Black Widow in 2-player. MoS's ability to give away a treason card each turn is an auto win in 2-player
Having said that, however, MoS is balanced properly for multi-player because that ability costs 2 influence to use.