Magic pulls functionality from several top themes to put shared functionality into a reusable module.
Magic began as a desire for all front end developers to be given the tools to make their site performant, mobile first, and DRY.
But also, to help development-- to make your theming process easier. To give YOU the tools you need to make your site how YOU want it. Remove the parts of core that are frustrating, ensure your theme is how YOU want it to be.
And to enhance the open-source-ness of Drupal. We want to take the best part of these themes and make them available for everybody.
Aurora as a base theme was rebuilt for version 3 to work directly with Magic. It's purpose is to give you the proper HTML5 templates, a few minor tools to help development, and nothing more.
Magic is compatible with ANY theme.
It's purpose is to be reusable, and easily implemented.
Always test your theme-- but most of all if you are doing work in your theme that you think can be reusable--- submit a ticket. This is how we know what people are using, and how we can make it better.