Rite Aid recently had these cool "colorphase" polishes. One side is a color. Another side is a color changed top coat.
This is 1 coat of the purple one.
This polish is a really pretty purple shimmer on it's own.
I put one coat of top coat over the pinky and middle finger.
With the top coat the polish turns a much more vivid shade of purple.
The brush on the top coat is basically a striping brush. I can see how you can use the brush to make cool designs on the nail.