Its already been broken. That scaling bug was actually over the top- try like 400mil thorns instead of 44 mil thorns in T4. You can still get pretty high Thorns number, since Thorns benefits from primary stats.
I find thorns strong but... inconsistent. They need to attack to work, with non crit every time they hit me it does 500k damage. Crit from Iron Skin does 21m, but because Iron skin last for such a short time it doesnt always work. I am (if i want to be) sitting at 21k thorns at the moment. I have most of the items OP has.