The Heralds of Magnora are the collective group of Soulless and Primal Gods that were discarded by Dynara in the time before the Great Silence, and were tasked with assisting Magnora in consuming all which Her sister brought into creation.
At the onset of the Elder Wars, the Heralds moved through the Void on a mission to consume the divine essence of the Elder Gods who inhabited the First World. After the first battle between the Soulless and the Elder Gods, it was discovered that the forces of creation and destruction - aspects of Dynara and Magnora - had left the realm when the Daughters took off after their Nameless brother. This meant that nothing was ever really created or destroyed, and life and death had not existed since Their disappearance.