well when i comment i made this suggestion kind of pair with port effect voodoo suggestions. lets say Captain D's or William One Eye's port suggestions approved with this one.
They used it on a port and all trading fleets which visit that port gained 3 danger penalty. with this card you can cast this on your guild members and at least you will help your friends in case of emergency. This needs teamwork and cooperation in guilds.
All suggestions are legendary cards. So in my opinion one for attack one for defense. It seems fair to use it on your teammates and effect all fleets.