Custom Action navigate to edit form using GUID

Using a SPD2013 workflow running against a Task List, I am creating a list item in a list called 'Employees'.  The GUID of the new list item is being captured as a workflow variable.

In a later task I would like to be able to provide a link to the EditForm of the new list item using a custom action button.

What is the correct syntax for specifying a URL to *another list's* EditForm using a GUID, similar to 

> /mysite/Lists/thislist/EditForm.aspx?ID={ItemID}

but what I am after is something like:

> /mysite/Lists/*other*list/editform.aspx?GUID=*guid string*

Thanks for your help