Divination was the name for Nod Tiberium technology during the Second Tiberium War. The process was developed in order to create the perfect human, and was heavily based on earlier Nod research, from project ReGenesis.
Basically, Divination was a controlled injection of processed Tiberium into human bloodstream. The Tiberium would act as a mutagen and slowly mutate the subject. Due to this control, the mutation would not be random and rampant (e.g. transformation into visceroid) nor unpredictable (e.g. the Forgotten), and the resulting subject would be, essentially, perfect. The pinnacle of the research was the World Altering Missile, which contained a warhead capable of transforming the world at an atomic level, from carbon based to Tiberium based life.
The missile and much of Kane's research was destroyed, while some was salvaged by GDI after the end of the Second Tiberium War. However, Umagon had progressed already into the final stage of the Divination process. The experimental vaccine created by Tratos to halt Tiberium mutation was ineffective, and may have contributed to Umagon losing her sanity shortly afterwards.