I might be misunderstanding what you’re asking, but it’s a hero leveling up. But I wouldn’t put too much stock in it, since there’s a ton of under-the-hood catch-up voodoo xp and autoleveling. I don’t like it, but that’s mostly because I can’t follow it and therefore don’t understand it.
That’s a good question and I’ve tried tests swapping between characters, but it seems like it’s attached to a single character, which is probably why you’re asking. It doesn’t help that I don’t understand how the cardplay works, because the game won’t tell me. Are combo cards added to the deck or do they just appear in your starting hand? When you discard them, can they cycle back around? When they’re used, do they go to the discard pile to cycle back into my hand, or are they one-use? How many are in the deck?
Again, for some reason I don’t understand, Firaxis keeps the cardplay mechanics under the hood. I have no idea why that is and I’m uneasy that it might become an issue later.
You’ll probably have to take a look, but I seem to recall there is a “backgrounds” option for comics covers. Frankly, I’d be surprised if there are fewer features than in XCOM’s poster editor, but dumber things have happened.