Currently doing a playthrough with this mod right now and went to fright Pyrogen. Everything was working fine in terms attacks and visuals, the problem was that the boss was dealing 1 damage to me. Even with no accessories and no armor the boss was still dealing a measly 4 damage and inflicting no debuffs (I'm not sure if it is supposed to inflict any debuffs or not). This applies to all modes as well (i.e. Expert, Revengence, etc.).
This post is mostly just to bring awareness to this problem and I hope the mod author sees it since as of right now Pyrogen isn't enjoyable to fight at all.