Is there a reason why a Dark Legion player would not be able to have HARDINGS INFLUENCE in his/her deck ?
Nope. Any player may play HARDING’S INFLUENCE, no matter what their affiliation. INEFFICIENCY Can INEFFICIENCY be played on an Establishment that has only blue icons so that it generates less of their product (for example, it has 3 food icons, but with INEFFICIENCY on it only generates 2 food)? Yes. INEFFICIENCY can be played on ANY Establishment (except those like IMPERVIOUS ROCK FORMATION, which may not be affected by any cards in any way), and requires ANY one extra resourceof your choice.