Rules FAQ

Naval Superiority makes you treat the "base" gold value -- not the "modified" gold value -- as if it were 0. So an opponent with a Kingdom plot, 1 Roseroad, and 1 Littlefinger in play would count 2 gold.

This card belongs on a long list of AGoT cards that need to get banned. Is the card overpowered? No. It simply ruins a game. I can only think of a handful of decks that can come back from a zero gold plot much less a zero gold opening plot which is when this card is most often played. So, you go through all the trouble to shuffle, deal, mulligan, etc. only to concede when the first plot is revealed. So much fun...