Counter-heroes in duel mode (3.1).

I have a question. In a duel, Iris is practically unbeatable. I only managed to defeat her with Ravenna, and even then, only once. I heard that Deidra is a good counter, but I highly doubt it, as Iris has decent resistance. Can anyone share their experience and name a counter that defeats her 100%?

Yes, and Ossir is also an option, but frankly, he's just as overpowered, so please don't use him as an example.