Fuck La-Mulana, I'm 35hours in and I'm quitting now. I'm gonna watch some random person's 2012 playthrough, 'cause I'm not having fun.
Friend told me the thing I was repeatedly dying to is immortal, I just need to spawn it and talk to an NPC to get an item (that I already knew I needed due to the rock-mural-sign-messages-whatever, but didn't know how to get. I gotta trigger the motherfucker).
The way the game tells you that the dude is immortal is by flashing him exactly like mobs getting damaged whenever you hit him, but blue instead of red. Not like, the "clonk and no-flashing", like everything else that you hit but don't damage, like armor and other shit.
Fuck, this has some very... INTERESTING... game design decisions.