I think it was mentioned in the REG that for the purpose of use the card becomes only the color/alignment that is in use when it is in field of battle / territory, but while in deck / hand / discard pile it can be targeted as either.
E.g. Seven Years of Plenty is played in territory off of a blue Hero. While in territory for 7 turns it remains a good Blue enhancement. Once discarded it again becomes a Blue / Gold Enhancement and can be targeted as either.