Here's where having a variety of tools comes in handy.
Careful bending with pliers works.
A rod/dowel (first time I ever heard of using a Sharpie), anything you can use to get the case mouth back "close" to round works.
Here's a tip, before running the "straightened" case into the sizer die, run it into the seater die. The seater die body is a little larger than the sizer, and will more easily take a slightly out of round case and bring it back round.
Then the sizer die can do its job, sizing the case.
I have also recovered badly bent cases (.45acp) by using the expander die in .357cal (extremely bent case) or .44cal (less bent case mouth), then using the .45 seater die, and finally the sizer.
bent cases can be saved. Cases where the brass has folded/creased, are pretty much toast.
Hope this helps