So grenades shouldn't kill you after the one who throws them is dead? It takes 2 head shots from thorn with the dot. 2 from fate bringer, vex, hawkmoon. I'm not sure how thorn is overpowered compared to them. The only difference is the damage from thorn is spread over time. If a hawkmoon was used you wouldn't have died the same amount of his only you wouldn't have had a chance to kill them as well...