As I've been writing an entertainer recently I've come to notice the lack of interesting spells to aid and enhance performances.
One of the things that came to mind when brainstorming was a ghosting affect. I settled on a spell allowing them to effectively paint the air, and as they progress in levels create longer and longer trails and duration before it fades away.
The affect would be translucent as if dragging a sheer fabric through the air.
If the spell was set as an application, something they could imbue an object or part of their body with it would become even more versatile, as on could apply it to their instruments and as they move and play the after image would drag lines of colour around the room, applied to hands, feet or hips the dancer could create an even more interesting show.
The secondary use of this would be adding it to weapon enchantments to have a trail following the path of a bow's arrow, or revealing the arch of a sword swing. Useful for training, but also an interesting flare.