Impersonation Step in SharePoint Designer 2010

Question

I have following questions on Impersonation Step:

1. How to use Impersonation Step in a workflow to grant/Revoke permissions based on conditions?
2. What are the pitfalls of using impersonation step?
3. How and when does it grant/revoke permission (if it makes changes to the current permission for the list item or creates a new group)?

Answer 1

This video on the Impersonation Step might help. http://sharepointsource123.blogspot.com/2012/10/a-closer-look-sharepoint-designer-2010.html

Answer 2

1. One can use conditions inside Impersonation steps, but you can't run whole impersonation step under a condition.
2. The only pitfall is the it runs under the identity of the workflow publisher, so whichever account you are using to publish the workflow, it should have necessary rights to performs all the permissions related operations in Impersonation step
3. It performs it's operations according to it's location in the workflow, and you can use it to change permissions on list items. You can add, remove, inherit from parent list or replace permissions on items.