Requesting (based on Otto's wording): Automation trigger: X days since last gift, filterable by badge + owner, with task/email actions

In essence, I want to create an automation where offline badged monthly donors who haven't given in 45 days triggers a task for the contact owner. I don't want to treat these monthly donors as pledges because we're cash-based accounting and we import or manually enter these monthly transactions. But I want a way for contact owners to be made aware that a donor has lapsed 45 days (6 months is just too long!).