Plant Yourself Like A Tree (Protection) V2

Armored Vest: A must play once pulled, given the amount of time you'll be defending, another +1 goes a long way.

Energy Barrier: Can help block any excess damage that defending doesn't cover.

Indomitable: Prevents you from discarding a card from your newly drawn hand after defending, and will more likely come up again based on the way this deck works.

Luke Cage: Block a huge attack with him to remove his tough status, don't let it be wasted on a measly one damage. Continuously use his 2 attack and when your deck is about to be empty, have him defend and die so that he is in the discard pile to be reshuffled.

Nova: With the abundance of energy cards in this deck, and how often you'll be attacked, this just makes sense.

Med Team: 6 healing over the course of 3 turns should give you more time in hero form.

Counter-Punch: A card that generates a physical resource or can give a free 2 damage to the villain when defending? Yes please.

Expert Defense: While Shield Block is better, as in it blocks all damage, this is a good alternative. When paired with Captain America's Shield and Armored Vest, you have a DEF of 7 for a single attack, which will most likely stop the damage. And if not, have Energy Barrier block one more.

Preemptive Strike: This is a ok card, only use it when you don't have a strong board state, or when a 3 boost card shows up.

Second Wind: Faster healing than Med Team, which can heal a very powerful hit if not fully blocked.

Tackle: Alongside Heroic Strike and Mockingbird, there are 7 cards that can stun the enemy in this deck. Save your physical resources for Heroic Strike though, 3 damage won't change much.

Thanks for reading this far! Let me know any changes you think I should make.