with multi attack+2 and 250 HP on Hit, my Thorns problem went away. later I added Harmony, so any MP replacement also helped my HP. at the moment, I only have 250 MP on Hit and 500 MP Regeneration with Harmony. my HP may go down from Thorns, but it wont kill me, and when my HP gets lower, that helps my Defiant Set do more damage. also, my HP is low, so it is easier for my on Hit and Regeneration to heal me. if you have high HP, Thorns will nock it down more, but having some kind of healing will keep it from getting to low to survive. just remember, Thorns takes 10% of your current HP each hit, so you need to either only hit the monster when Thorns isn't active, or have enough healing to keep from freaking out when your HP drops.