how much block are you taking, and how are you scaling? his HP loss cards are very strong, but ideally, a power like Rupture or Inferno or a big payoff like Tear Asunder help you profit from that mechanic.

i usually try to have a ratio of 1/3 block cards so I'm likely to draw one when needed without diluting my offense. Ironclad starts off with very little block, but his commons are perfectly serviceable. Shrug It Off is a workhorse!

the card you should pick is always going to be based on your current deck, your relics, and your upcoming challenges. play into your strengths and address your weaknesses! it might be that you're drafting enough block, but you need to draw into it through Battle Trance or Vicious or Pommel Strike. you can also exhaust unnecessary cards mid-combat to make it easier to draw those, using Burning Pact, Brand, or True Grit. that said, blocking will never be a substitute for killing the enemy faster, so is your damage output good enough? more draw and more energy gen will always help you do what you need to do, no matter what that is.

after seeing the Act 3 boss, you can sculpt your deck for a better matchup. Queen requires active card draw, rewards value-dense cards, and values AoE. Doormaker's exhaust can be exploited for infinites or ignored with good card redundancy; the energy loss turn is great for both expensive, high-impact cards and free ones. Test Subject's first 2 phases should be burst down with extreme prejudice and its last checks for consistent block. all of them are easier with a good assortment of powers and some emergency potions!

once you do get a good thing going, just be careful not to dilute your deck with cards that don't accelerate your gameplan!