shadow-box

Shadow-box works as both noun and verb.

A shadow box is a shallow display case with a glass front, used to exhibit memorabilia or three-dimensional objects: She kept her grandfather's medals in a shadow box.

To shadow-box is to throw punches at an imaginary opponent, a training exercise for boxers.

Figuratively, shadow-boxing suggests fighting something insubstantial or avoiding real confrontation: The candidates spent the debate shadow-boxing rather than engaging each other's positions.