An artist's canvas is a workplace to create beauty, disasters or any bizarre mix in-between. The artist's vision has no limits but those of their imagination and determination. With this limitless capability and endless range of outcomes, it is when an artist succeeds in truly executing their vision that it stands out the most.
When working with pieces created by other artists to create your own masterpiece, a work of art is like a puzzle with too many solutions. Marco found the solution to his puzzle, and though his pieces don't quite add up to a masterpiece, they're still a beauty to behold all the same.
Complimentary colors play a large role in the success of Marco's vision, with auras using Rarity's own scheme. The auras lack a bit of gradation when they connect, but they still work well together.
Going along with the color scheme, of course, her Cutie Mark floats pristine and 'fabulous' in the air, though being off-center is a bit visually jarring, and leaves a lot of 'dead space' on the left side of the image.
Rarity herself looks fantastic on the left, but on the right she merely adds to the problem of the dead space away from her. Though unobtrusively placed in the background, she's cluttering space that's being occupied by the center of attention: the cutie mark.
Though symmetry doesn't have to be perfect, this work could use some balance of focus and a slight changing of effects to bring out the best of its potential.