Iron Man J.U.S.T.I.C.E.

Stay as long as you can in the early game in alter-ego to assemble your suit. Cards such as Counterintelligence, Under Surveillance, Foiled and your allies (Daredevil, Agent Coulson, Nick Fury and Jessica Jones) should help with that. Even with all that, sometimes it can start to feel you're putting yourself in a weak position, but it was always worth it for me, as assembling your suit is crucial and to some extent you're actually in a much weaker position in the early game in hero mode with lower hand size and low health.

Once you have your suit assembled, Iron Man just feels like a power house and can both remove a lot of threat with Heroic Intuition in play and do big burst of damage with Repulsor Blasts or Supersonic Punch (for this one I either use of the spare Rocket Boots or the wild resource from Quincarrier to make IM aerial and maximize on the damage dealt).