The Magic Pen allows ad-hoc markup within an approval for real-time collaboration.
These annotations are not saved, and primarily used within the session or real-time discussion.
Any user viewing the the same approval on the same page (and in the same approval group) can see and draw annotation using the magic pen. Any user can also delete all these magic pen annotations.
This is useful for real-time discussions, where reviews and approvals can easily share their views by marking up / drawing on the document or image without having to add save an annotation.