What shuts off dupe saves other than Brienne and Burning Bridges?

Fortified Position?

Neither Burning Bridges nor Fortified Position have any affect on dupes. Each only stops printed text, not gained text/abilities like dupes. Short of Brienne, your best bet for "preventing" a dupe is to use a "cannot be saved" effect.

Like all other triggered character abilities, you're going to have more luck finding ways to cancel the dupe than to make it illegal to trigger in the first place.

it was at my Store Championship in Bloomington...you were playing Conquest, and something came up and you said that it prevented the save, and I'm wracking my brain trying to remember what it was.

Or maybe my memory is faulty, and you were correcting me that gained abilities don't get blanked.

Now that I look at the exact text I think it was an instance where I had Burning Bridges up, and you clarified that the word "on" has been ruled as "printed on."

I remember the "Burning Bridges doesn't stop dupes" discussion in Bloomington, but not one about what might. Sorry.