Bloody Bess:
95-99% of Marvel fans have no idea who she is so it would come out of nowhere. I can see her fighting Doom due to the Crimson Pirates having been captured, last I saw her, she was on her way to rescue her crew. We need another "evil" character, way too many heroes lately. You can also add Nightcrawler to the package as well since they were lovers but I don't care about him.
She could be either a strategist or a duelist. Mixing her mind abilities with her Martial skills would be interesting