The wave is one of the few cards never used in the manga or anime. It has the ability to create gigantic tidal waves and to control the oceans current. It is able to control water near it but unable to create new water like Watery can. It can be combined with The Watery for a deadly effect.
The Wave is under Watery.
The Wave is transformed in Episode 53 during Sakura's frantic wave of transformations.