Angry Maid Kills Animal Murderer (Limbus Company MD4R) 

There is no way in hell that any other battle can be worse than Dongrang in MD4R.
When the trees are super buffed and take no damage, the battle is suddenly a massive threat, and you can't managed 8 targets with 6 slots.
As a result, I found it way more viable to try and solo, and even then, his finishing skill is insane and is basically a 50/50 no matter what I do.
He becomes a lot more manageable if you're using bleed or burn, but holy hell does he SUCK to fight with poise (even moreso when you don't get clear water, which I didn't.)
I spent 3 hours on getting that solo.