How to defeat rumble in russia boss without friends help

As before its easy to complete all four boss with an ease without any problem.
If you are low level player with less stamina and skill points you can get the mastery loot by assiting your friends in there boss fights.


And also bookmark this 
BOSS HELP


this will automatically heal you when you are in boss fight...(credit goes to spockholm) for making this bookmarklet.