Whispershades

The sudden flow of water often raises the marsh gases, which are usually trapped below the water's surface. The gases are a well-documented phenomenon created by the decomposition of vegetation. They are noxious to human health and easily flammable. At night, the Morgunt Marshes can lit up with Fools' Lights‌.
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‌ The lights seem to dance on the surface of the water. From afar, they can be taken for lanterns and a sign of habitation. These lights have caught the unwary travellers in their traps countless times, so much so that in folklore and legends, they have been portrayed as evil, vengeful spirits called Whispershades.
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Some of the Whispershades can actually be magically imbued see 'Secrets of the Marshlands' in the 'Putrid Tide' article.