Farmer’s/knight’s base is 120. 2 star @ lvl 11 is 160. That is exactly ’nuff to absorb 60 damage hit. Factor in attachments with flat damage reduction, so it is closer to 80 damage hits. Steelbrow is a thing. And proper mdef bros should not fail more than 2 5% rolls per turn. (2 avg damage swords/flails/mace hits).
That idea formulated exactly with game breaking parameters. Nerf it a bit, and it could be not game breaking, but it may become of questionable use.