Supouse you have a checkout of your app and you have to deploy it to four servers; and after each deploy you have to run some tasks, like fixing file permissions, creating symlinks, etc. You can define all this on Magallanes and with just one command you can do all this at once!
Easy boy. It's not sorcery, just some technomagick!
In Magallanes you define environments like "production" on the example above. Then, on that environment configuration, you set up to which hosts you want to deploy, and what tasks to run (after, on, before deploying).