Effing Moonchild breaks the effing arena

[Yup]

It's the Sacred set on allies. The Sacreds .... "% chance to grant allies heal shield for 2 turns when taking damage".. or it cleanses and grants it all to allies upon death....those buffs get applied to Moonchild even though you can't see them. I also think he's getting Perfect Health at times.. and Cleanse... Moonchild will also take damage after he attacks at times as if from Punishment or Burn buffs or something - not a lot of damage, but clearly damage. And Marks work on Moonchild even though you can't see the marks. All the buffs work for the most part, they are just invisible. I obviously can't verify some things like Corruption or Ascension... but the standard red/blue/green/orange/purple buffs all seem to work.

Yup, I've only been playing this game for just over a year. Do you remember another character that was as problematic as Moonchild (and I know you have argued that he is not that problematic if you bring multihitters). I was just curious if this is an isolated incident or a recurrent thing.

The Prisoner and his passive has always caused unexpected issues.... since I started playing. The fact that currently the Prisoner doesn't seem to have any major issue is kind of not the norm. Prior to last months update, the Prisoner was disabling all passives on all enemies, ignoring Singularity talismans and immunity. Using him was one sure-fire way to kill Moonchild or any team with Moonchld rather easily. (This no longer works though)

And for Moonchild it's specifically multihitters that cause Moonchild to heal... see above If you only hit Moonchild with a single hitter, you can whittle him down, even if he has Vampire.. assuming you also have a max-awakened Moonchild.

Single fighters left..... Moonchild + Labyrinth + Echo, manually ALWAYS beats Moonchild + Labyrinth + Vampire, AI -- manually you get more "prefect" hits and Echo grants you more turns. If it's Moonchild v Moonchild, the vampires, when they do heal, don't heal for as much as if they only hit 1 opponent. It's when they hit 2, 3 or 4 opponents that they pretty much full-heal the AI Moonchild. He's actually harder to kill if you have more allies alive.