The Devouring Earth by V. von Grun
This scholarly research paper was written by Vernon von Grun, a disgruntled lab assistant to Operative Grillo with dreams of becoming a full-fledged mad scientist. Fortunately for him, he had a resource like you to help him work out
Von Grun's Science
The paper is remarkably well written, given Vernon's tendency to rant about science at strange moments. In the paper, Vernon details how the Devouring Earth work in great detail. Apparently it all starts with a semi-intelligent bacteria called 'The Will of the Earth'. Colonies of it completely re-write the genetic code of an infected creature, given sufficient time and nutrients. What's more, the Will of the Earth is able to communicate with other colonies, forming a bacteriological telepathic network. The added intelligence of other colonies allows the Will of the Earth to create larger-scale changes to creatures. Colonies of Lichen infected with the Will of The Earth are able to animate Rocks to form rock-men, alter the DNA of trees and fungi to create plant creatures, and even take over insect colonies to form cloud of stinging insects. The greatest transformation is that of the 'Devoured', human being who have been re-engineered by prolonged and forced exposure to the Will of the Earth. Von Grun spends some time on them, and show how the process of 'Devouring' works, based on the information he gained from Pyriss, the devoured ex-heroine you captured. Von Grun also posits that the entirety of the Devouring Earth forms one single intelligence under the creature that leads it, a blob-like being called the Hamidon. Vernon promises to follow up on his theories of how Devouring Earth could be used by Arachnos as a terror weapon in his next paper.