Here are some use cases:
How often has a product been viewed that was advertised in a campaign?
Filter the metric "Qty Product Views" with the parameter and add the metric in a time analysis.
Go to E-Commerce > Products and apply the filter:
What percentage of orders included an advertised product?
Create a custom formula under Custom figures > Custom formulas.
Use the following setup.
The metric "Qty Orders Advertised Product" uses the following filter: