I can not verify if this is true because I have not done the Thorn bounty.......but this is a GREAT tip if it is true...... Get 2 friends....I know that is challenging. Go into Skirmish. Run as a TEAM. Tell them to let you get the killing blow when possible with any kind of void damage you have. That part was obvious but the next part is GENIOUS ( If confirmed ) IF YOU DIE...have your team revive you and it will not take the -2 points off of your score towards the bounty. This will probably help your progress greatly. Plus you would be surprised what minimal team work can do for you in Skirmish. I am bad at PvP but with 2 friends in Skirmish we can do pretty well.