Blighters, a type of druid, use Dark Nature magic. Their spells are powered by dark nature energy; an energy that draws out the nature energy of plant-life around the caster.
The origin of the Blighters came about from work done in the Mauhúl valley. At the time they were not called Blighters. They were simply mortal and angelic druids working on a way to reduce the demon's great numerical advantage. These druids, along with alchemists and others, developed a disease called the RT-12 Leech. Plants were the vector, with each new growth giving rise to an infected plant. A decade later, the plant vectors were all over the valley. It was so bad that both sides abandoned the area. The research done in developing the RT-12 Leech and all its predecessors led to an understanding of how the streams of nature energy in a plant could be tapped. This knowledge eventually got misused, leading to druids using spells that sucked the nature energy from the plant-life around them. Nobody is sure when this started, but it is thought that those lacking the mental facilitates to cast druidic magic, took the easier path to druidic magic, using dark nature energy instead of nature energy.