At that moment the drizzle eased, and Ledoik could see as plain as day a blight upon the fields near the edge of the forest. Like a rock dropped into a pond, a wave of lighter shades of green emanated from the blights centre. Growing from the forest, where it was darkest, the field got lighter and lighter the further away it was from the blight. It was clear enough. The commander barked words, organising the archers, the few catapults they had and the giant rockslings to this side of the battlements. He motioned them to aim towards the blight, the dark patch near the fields edge
Extracts from Alkur’s book of insects.
The best thing that can happen when confronted by a Rhaphi (Rafy) is that it will ignore you and continue on its way…It seems to have no purpose in life but to transport its undercarriage of parasites, which are numerous and not exactly friendly or hygienic, from one place to the next.
If you want to add a "supernatural" touch to your campaign, define the rules of magic and the universe. Make your players comfortable with those rules. Then your new supernatural creatures must then break those rules.