This is a specialised super soaker that fires Anti-Wisps made of water. The Anti-Wisp is link is in the comments section below. This fires these. They obey your commands in combat and only in combat against Wisps. If you summon one using this item and you are not fighting Wisps, it leaves you and seeks out the closest Wisp on this plane. If there are no wisps on your plane, then it acts in a way deemed appropriate by the DM.