The ion-deployer plugin uses the iON REST API to deploy your application. It runs as a publisher at the end of the build, only if the build is successful. First found mule application will be deployed in case of a multi-module build.
You can define multiple iON accounts in the global configuration section.
Then in the job configuration for the application enable iON deployment by selecting Deploy to iON. You will have to select your account and provide the target domain.