Hello!
Some people think it is funny when you fight with bosses on map (example Rubric), they pull the boss over the range and it is will reset. 2x i got this.
Idea: Shield on boss territory and you cant attack him outside the shield, or can’t aggro the boss outside the reset range. If no one attack him 20-30sec or every player leave the boss area, the health reset. Or something, it is my idea. Maybe should work 
Thank you and have a nice day!