As the title says it is required for more synergy from other gear, neither from just % of your Vitality, wich is almost constantly near 5000+ points.
Now if we take this number and doing some math we’ll take 15k Thorns only! It is not so much for 70lvl chars. (But it good only when you level up from 9 to 70)
Since the Game have shields with their % Block chance and a ring JUSTICE LANTERN with it too.
I propose to change Ironheart’s Vitality bonuse to %Block Chance! For more thorns, but not for free! There’s a challenge - pick up more Block Cahnce - get more Thorns.