Got my ass handed to me against Ultron the other day. I was playing solo Aggression Captain Marvel, and I went in blind against Ultron. I hadn't played against him yet and decided to not even look at his schemes. It was a fun way to go into it for the first time, as I was figuring maybe Captain Marvel just stumbled upon Ultron without knowing what he was up to.
Got him down to his second form in no time flat, but not knowing that his final scheme only needed 5 threat to win and that I couldn't remove threat really killed me. I tried keeping him on his first scheme for as long as I could, then when he finally got to his second scheme and I saw it needed 10 threat I relaxed a bit, since I was handling the drones fairly well at that point.
In the end I just got overwhelmed with his drones though. Then I got that card that makes all of his drones gain +1 in every area, with 4 drones on the board. If only that card hadn't entered play I might have won, because I had Hulk deal 1 damage to every character. In ordinary circumstances, that would have been a very nice drone-clearing attack, but alas.
Really cool villain. He plays just like I would have hoped, and I'm looking forward to taking another stab at him. I think Captain Marvel is good for the job in solo, but I'm not sure if Aggression is the way to go. She may need a bit more threat mitigation, so I'm thinking of going with something else next time.