Thought I'd make a post containing all the hero and gear changes that happened when PVP season 2 was introduced since I couldn't find a page with it all centralized.
- Mockingbird now has a limit of one extra turn she can get from tactical insight.
- Emma Frost's diamond body no longer prevents debuffs. Only lowers damage received.
- Black Panther's Panther Stance is now a quick action.
- Dr. Strange has a new passive buff, Sorcerer Supreme. Makes some attacks quick actions and restores stamina. Also has a new uniform and class, Tactician.
- Spider-Woman's Vengeance is now a quick action.
- Captain America no longer has Lead the Charge. It's been replaced with a passive buff for a chance at damage reduction. Inspiring Leadership (for both teams, in PvP) will be applied to team members after the first action by anybody.
- Quantum Jumper no longer grants the agent an extra turn. This may be bugged at the moment - I've noticed my agent getting an extra turn the second time QJ is used, but only sometimes.
Those are all the changes that I've found so far, let me know in the comments if I've missed anything.