Sprites

Sprites are a strange phenomenon that takes place in the world of Ostara. Sprites are small colored wisps of light that appear and reflect the strong emotions of large groups of people and the land itself.
Sprites are like strands of web or silk that connect our material world to the spirit realm and the shadow realm. Sprites can be composed of either Od or Vis, but usually a mix of both.
Sprites are the true cause for the large surge in demons or ghouls after a large battle takes place between two warring factions. The large scale combination of suffering, hatred, dread, and death draws out a reflection within the sprites that match those emotions. Thus large amounts of sprites made of vis will permeate the battlefield, combing through to latch on to the most hate-filled or vengeful dead whose spirits haven't crossed over to the other side yet.