Documentation

This action initiates the specified workflow for one or more list items in any list in the current site collection.

1. Site – select a site from the current site collection. Use runtime value to specify site URL only known at run time.
2. List – select a list from the selected site. Use runtime value to specify list title only known at run time.
3. Item – enter at least one filter value for selecting target list items for applying the action. To select a single item use the ID column.
4. Workflow – name of the workflow to run.

NOTE: In Office 365 you might need to activate the site feature "Workflows can use app permissions". It will ensure that when the action calls the workflow while running under app permissions (either using Impersonation or running on the timer), the workflow will be able to use those permissions to access SharePoint.