First you need to follow the team requirements for the stage because mod here at this stage is also affecting the boss because of its skill, skill that drains it's hp while it do dmg to your team so the key here is to survive while the boss drains it's hp. What I do is first I set the mod to x100 each then used the dmg dealer kemono I did make the hp of the boss half from the first attack then follow of my other assaulter kemono then I used my tank to add buff best with shield next my other tank so you got 4 deployed and you can see the boss from here is it's hp slowly drains next set the mod to x1 each then catapult your healer to the above ground not from below so she won't die deploy the last two until the boss dies. I don't know if this helps or one of the solution do experiment though.