I got it too! It's the bombdiggity. And yes, the SS makes it almost seem OP. It's fragile, though.
Fragile? It's got 4000 HP, 4600 DEF. That makes it a tankier monster than most. On top of that it's got HG then both lifeflip unlimited 130TU and desperate bite 100TU. If I'm not mistaken that's the only 100TU desperate bite in the game... it's 160TU for everything else (maybe chronotitan got his reduced?). Take account of stun immunity and this monster is reliably going to get turns regularly where it can heal itself if needed. Sure, it can be put to sleep and is weak to poison but practically every monster is weak to those.
So I have to politely disagree lol I guess it's not like Utopian which is arguably the hardest monster to kill in the game... 4350 HP, 5900 DEF with HG, overwatch and a way to instantly heal itself 5 times then use overwatch again hahaha. That's probably a more reliable monster to survive 400s to be fair!