Gunfire Reborn

If you're doing It co-operatively, you can sit one out before entering the boss door.

I just sat out without entering the battle arena due to the golem being the most glitched boss I have ever seen

(I was the host of my lobby, never defeated it before due to the glitch of not being able to aim and fire. Apparently best for the host not to play and not to use any decay/poision weapons)

Get your friends or teammates to clear out the boss for you and respectively you will get this achievement, you don't need to enter the arena or damage the boss at all to get the achievement.

Of course be considerate for yourself and teamates, if they're not experienced enough they might struggle even defeating the first boss, eventually meaning you will have to intervene and actually try to finish the boss without taking damage

Best of luck. :) fun game so far