The Harper Symbol

As a bonus action the caster can touch a nearby object that is at least 8 by 8 inches big and is flat to imprint the Harper Symbol (A harp and crescent moon) on the objects surface.

The symbol will appear on the surface of the object for half a minute before vanishing the caster can dispel the symbol earlier than that if he likes. 

While existing the symbol will give off a faint light blue glow. After vanishing there are no traces the symbol was ever imprinted in the first place.