The game just offered me a Marius card pack for purchase, even though Marius isn’t available as a champion yet. They mixed something up when pushing out Semira... she doesn’t appear in the “searching for opponent” animation, but Marius does, like Rockchick noticed.
I think I like the Semira deck the best, although I lose most games since I don’t have many high-level cards in her deck yet.
Once the Marius pack is available, I think that all of the major characters from Awakening and Blood Wars have their own cards, except for Michael. If they add any more champions, it seems like they would have to go with Michael unless they expand to include previous films. I suspect that the filmmakers told them to keep Michael out of the game though...