I didn't have Hizi high enough level for her to even be "just drained down to low level". It straight up ended the game and gave me the catzilla ending. Geeb is right that the boss has far too many mechanics in its favor. Taunting doesn't work half the time, as the legs stomp whoever they want, AOE from the tail doesn't even care, bleed and burn take away from your severely lacking turn economy to counter unless you want to just soak up an immense amount of damage, drains heal for an exorbitant amount which puts you at a health, level, and turn disadvantage (cause in the multiple tries I did to beat the stupid cat, I only struggled free ONCE EVER; so you may as well just count that character as lost till phase change), and having to chew through multiple thousands of health to get to any meaningful damage in the span of 2 turns is not only unreasonable, but there's only 1 or 2 strategies to do so. This is an unescapable fight, which means you HAVE to fight it out. If you DON'T immediately gameover from losing it, then you may as well be since you're just put back at the beginning of the game. Have fun grinding back through the slog of enemies just to encounter the same boss, but now even stronger since it gobbled your hard work from before.
Here's some questions for you:
Why do the tank enemies have so much damage output, apply debuffs, and have self-sustain? (Bleeding heals, for whatever reason. Not even just for the vampire bat enemies, but the starting area pigs, too)
Why do the healing enemies have high damage AND a revive?
Why do draining enemies have buff abilities and spawn in multiples during a single venture?
Why do structures outclass your entire team? A draining totem is pretty much a death sentence for a run if you don't take it out in 2-3 turns.
Why are there buffs that are far better than you as the player have access to that don't have duration and will quickly overwhelm you? Looking at you, overclock.
Why have enemies specifically around that steal your items, that are so polarized in either completely useless/near mandatory, which are nearly impossible to get due to the cost and rng of the shop, and you have no hope of stopping them in the early game?
Why do you, as the player, never have advantage in any fight, no matter how deep into the playthrough?
It's hard to believe you just shrug off a lot of these frustrations unless you just do not value your own time or enjoyment of a game, and are just saying this as inflammatory dialogue.