During a recent run, I noticed taking double damage randomly. While farming coins with a curse room door, I noticed that I often lost a full heart along with playing the necronomicon noise though that might also have been caused by a gulped strange paper activating the negative. What could've caused this? I'm guessing that it's caused by this mod, since before the run I saw this
reddit post of someone having the same double damage issue, as well as having fiend folio installed.