Haha, I just spent a fruitless 30 minutes (and why I'm laughing about that I don't know!
). I went back to playing, and noticed that enemies were getting hit with something called "Fatal luck", which put some random curse on them. I thought, "uh oh, I must have messed something up in the code somewhere". So I went back and kept tinkering with things to figure out what I'd done wrong.
Well, long story short, it turns out I had the "Chain of Chance" on, which - apparently - hits an enemy with a curse any time they hit you with a critical hit. The description is horribly wrong, saying just that it "curses enemies, inflicting critical strikes". What it really does is curse enemies when
you get hit with a critical strike. Of course I hadn't seen it yet, as the enemy never critical struck anyone thanks to the bug.