On their own, the Deep Caverns are cool. A bunch of abandoned laboratories with shady shit going on and some interesting lore dumps. That's where the positives end.
Not only do you have to deal with re-spawning enemies, not only do you have a constant debuff, not only will the Faceless not help you if you played the game well, not only do you have to do a shitty scavenger hunt, not only do you have to constantly backtrack to manage the power, not only do you have to do some random chemistry shit (and another scavenger hunt) but then to cap everything off you have to fight a truly awful final boss.
I've never been a fan of 'big dumb object' bosses, and this one is the biggest and the dumbest. Regenerating AND re spawning tentacles that are tanky as shit? PLUS random mobs attacking you all throughout?
I can't do it. Maybe if this is what I faced right off the elevator I could get through it, but after spending six hours trudging through the worst gaming experience I have ever had I just can't. Was Styg high, drunk, or filled with malice towards all Mankind when he designed this part? Banging my head against a wall would replicate the experience, it might even surpass it.
It's such a shame the game has to end this way. It was really good! But like many good games, it shits the bed in the end.