It’s easier and less likely to have this happen if only 1 person, the person taking the buff shoots his staff. Everyone else just plays for their lives, giving the call out, staying away away the dunk corner and clearing the annoying taken. When your buff person has gotten the 4th symbol start hammering the crit spots then damage/ kill. You have plenty of time with 5 players shooting the crits as it’s the leg one which takes the longest to break. Extra loose bullets from other players whilst trying to hit crit spots during his symbol phase can cause the boss to start constantly sprinting around and not stopping to plant his glaive. Players who accidentally get buffed will then die as there will be no symbols. This works well and is how I am teaching the damage encounter.