Forum:Once per turn cards

Once per turn cards
Question about the Black wings, since most of them, or all of them, not sure, have the "once per turn" phrase, does it mean that the effects work on both the owner and opponent's turn? Or just the owner's turn, cause from what I think they can only activate it on their turn cause it's their card and not their time when it's the opponent's turn? So can the effect be used on both players' turns?