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.
There is also the option to leave all libraries within the header, which may be needed for some modules.
Put all of your theme settings in code, to allow them to be stored wihin your version control.
For development only, allows the theme registry to be rebuilt on every page load. Useful for active theme development.
Create responsive designs quickly and efficently. Displays your width in pixels or ems.
Useful when used in conjunction with Modernizr, allows you to quickly see classes on the html element.
Currently working on allow sub-theme creation through Drush. This will be a port of Omega's system, and be able to be used by any base theme.
There has been a feature request to allow CSS and JS removal to be customizable by page. We are working to see if this can be possible, and still retain Magic's performance.
Now that Drupal 8 is becoming a reality, we are starting to begin development on a Drupal 8 version.
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.
Magic is compatible with ANY theme.
It's purpose is to be reusable, and easily implemented.
Magic came from development of many base themes. We are always looking for what other themers are doing, to see if it can be reusable. If there is something you are looking for, submit a ticket.