This looks really good; clean layout and relatively straightforward. I appreciate how much effort you spent exploring the theme. I think as a reader, it's helpful to introduce the myth before the actual stat blocks, as it can be hard to hold everything in mind without a broader context. I think you also might want to indicate on the trifold that this is more of a bestiary than an adventure or quest. All in all it's great, really interesting idea, really evocative descriptions and execution and lore, could definitely see myself slotting this into a bigger quest as a cool fight payoff!