When creating a level metric on the fly (Derived metric inside a report), there is some syntax you need to know for the different grouping and filtering options.
The table bellow shows the different options:
You have multiple MicroStrategy iCubes that you want to be able to refresh from your ETL process, which would allow you to refresh them only when certain criteria have been met (like after data load has been successfully completed)
Using the Command Manager tool you could refresh each cube separately, but it might be easier to have all cubes refresh when a specific Event is triggered.