Four things make the thorn a bit too much of a force to be reckoned with in the crucible. 1. One headshot takes down atleast 2/3rds of a guardians health. 2. It more then doubles the time it should take for your health to regenerate if you get hit by it. 3. The range barely sees a falloff in damage due to the Burn damage. 4. It's a 3 body shot kill with burn where most handcannons would require three precision shots to accomplish a kill. A reasonable adjustment to the thorn would be these two things. 1. Make precision shots required to have the burn damage kick in. 2. If the thorn user dies the DoT should stop.