Phase is a Pentaho Analysis Editor - essentially a mondrian schema editor which can be run right from inside the user console of the Pentaho BI Server.
Here's a quick Youtube demonstration of what you can do with Phase:
https://www.youtube.com/watch?v=2ZRkOkOFjqw&feature=youtu.be
Phase is available via the Pentaho marketplace. To install phase, make sure the marketplace plugin is installed. Then, open the Marketplace perspective and install these 2 entries:
You can also manually install Phase by following these instructions:
User documentation is being created and integrated with Phase, and will be avilable from within the Phase application.