Captain America

I've been tweaking this build and I'm finally pretty happy with how this performs. So far I've beaten on solo mode expert Claw, expert Taskmaster, and Heroic 1 Rhino.

Early game, you just want to get setup like normal, flipping between AE and hero form as necessary, but once you've set up a critical mass of defensive upgrades, (i.e., a shield, unflappable, electrostatic armor, and some other form of damage evasion, either from response events in hand or something like defensive stance on board) your goal is to stay hero form and defend against every villain attack, in the process drawing an extra card and doing 2-3 damage to them. With the retaliate and energy barriers, something like a measly arms runner does 0 damage to you and dies instantly without you even blocking. Captain America's ability also works really well with the M.O. of the deck. You don't have an indomitable or desperate defense? No problem, just discard a card to ready him up if you need to thwart or attack during the player phase.

The only thing I'm noticing as I play this deck more is that I originally thought desperate defense was a slam dunk 3-of, but it really is only good early when your full defensive upgrade arsenal isn't set up. Later on, I dislike that it's a 2 card investment to ready your hero, which significantly hampers your next turn. Especially since it actually prevents you from using your energy barriers, which you sometimes want to use to actively be using to push damage. I could see myself cutting some number of desperate defense for the last defensive stance and/or a card that generates a mental resource for black widow.