Fortress America

Defence can be a struggle. It can keep you alive and so control threat by staying in Hero mode. It has no tools for reducing the threat that does inevitably accumulate so things can go tits up.

Cap. solves that problem by being able to thwart for 4 himself lots of the time for the cost of one whole card. This tips him into respectable threat control territory.

With protection he can keep his allies alive using Med Teams and get a lot more damage and thwarting out of them. He can tank very well - if you need to defend "I can do this all day " helps with offence, thwarting and recovering. Even so you will use it less than half the time especially as you set up. He has enough tools to create stun locks once he is established but getting there is easier because of all of the other assets. Energy Barriers are especially strong; together with retaliate & Nova they help him keep up the damage output when he only has a small number of cards that do high damage.

Stars

Shield - treat him as being one card down on set up but having 3 def and retaliate. Do not look back.

Heroic Strike - Good damage & stun is great.

Super soldier Serum - very nice resource generation

Steve's apartment - chip heals and card draw for cheap

Agent 13 - thwart 2 after removing 2 is good and solidifies the good threat reduction. Great with ..

Med Team - useful padding for Cap but mostly great for keeping allies alive.

Energy Barrier - the flexibility of offence and defence this provides is amazing. Against Ultron drones you can redirect one's damage into the next one & kill the first with retaliate etc

Nova - pinging attackers for 2 is good mitigation as well as damage. (edit: Probably more a solid as he is one off & somewhat expensive to set up & use)

Solid Fearless determination - mostly cycles but occasionally allows 6 thwarting or just getting to an odd total more efficiently

Shield Block - stops any damage which is great but overshadowed by other defences & heals in this deck

Luke Cage - can soak a ton of damage or attack many times for 2

Enhanced reflexes - good for powering up Nova on demand. Can smooth resource floods.

Mockingbird - stunning is great but ally slots can fill up and she does very little on the board compared to the others.

Lockjaw - respectable stats if you play him for pseudo -1 from the discard pile.

Helicarrier - good as usual, Mansion might be better. Does not seem to need both.

Energy Genius Strength Power of Protection - always handy. The fact power of is wild makes it worth it, though there are 8 cards that benefit from it.

OK Endurance - 3 hp is enough to make him feel more safe.

Armoured Vest - 1 extra defence can pay off, certainly feels nice.

Only play either if you have the spare resource

Shield Toss - the combination of minions and cards in hand that make it appealing does not seem very frequent. Another that is probably better MP. Possibly because there is no synergy with resource discounts/2 value cards it feels expensive even though it is pretty cheap on paper. This deck has next to no card draw which makes it worse. edit: updated from disappointing to amazing when it is good but situational. When it is good is against the Green Goblin who spams fat minions (unlike Ultron who spams very weedy minions aka retaliate fodder)

Disappointing

Counter Punch - 2 damage is a good return but often you would rather have the resource, or the villain is stunned. It is so much worse than Nova.

Pre-emptive Strike - good if you are not defending but flip a big boost - probably better MP

Indomitable - does not seem as good as it sounds. Another one for MP?

Bad Captain's Helmet - play well so that you don't need an "oh ****" card.

Why No? Avengers Mansion - it always felt expensive and the deck seems fine without it.

Nick Fury - the healing, plus Nova's ongoing effect means the allies often stick around. Luke Cage can last for ages even without healing. This means the ally slots are less free so the cost of playing Nick was a bit higher so he got dumped.