You can get this achievement relatively easily with The Ironclad. The approach I used to get this involved a defense heavy build, taking advantage of Body Slam+. Keep your deck lean here, you just want the basics so you can get as many Body Slams into your hand every turn. Prioritize removing Strikes, followed by Defend. You can keep a few Defend, and Bash can be kept to boost your damage with Body Slam.
In general, you want to take the following cards:
- Body Slam: As many as you come across. Upgrade them all. The 0 cost upgrade makes this your primary method of damage.
- Shrug It Off: Useful for the extra defense, and the card draw is a bonus so you can cycle to your Body Slams.
- Pommel Strike: You can take one or two of these. When upgraded they give 2 card draw.
- [Optional] True Grit: Gives block and can be useful to clear crud from your deck in longer battles.
- [Optional] Armaments: Gives block and can be useful to upgrade your un-upgraded cards. All the other cards in your deck are greatly improved through upgrades, so it can be quite helpful.
- [Optional] War Cry: Helps with card draw. Can setup your next turn, though with a lean deck, this shouldn't be a problem.
Relics:
- Dexterity relics like Oddly Smooth Stone are incredible, improving your defense AND damage.
- Extra energy relics are always great, as long as you can deal with the trade offs. Slaver's Collar and Busted Crown were helpful in my run.
- Relics that grant strength like Mutagenic Strength can be helpful here too, though less helpful than the above.