Automation rules should allow passing a value from one field to another field Merged

Want to be able to Pass eg; values from categories to a custom field either on Ideas or features based on a condition instead of setting rules for each value of the category.

So if I have 10 value in my category, I have be build 10 different rules to pass the values to a custom field as the current automation format does not allow if condition X, then categories.value = Customfield.value.