Knights of the First Lord
The new encounter that awaits you at the end of the Gilded Cave of Knowledge.
The knights ask you to react to each of their attacks with a specific dodge type, "Simon Says" style. This behaves differently from usual bosses, which let you use multiple options. Approach the fight with an open mind, and you'll take away skills you can use in the rest of your journey.
Be aware that this fight is optional and you can just leave. The Fringefolk Hero's Grave site of grace is unlocked for you.