The Shadow Horde is a threat to all within Kathalia. They relentlessly expand their territory to allow more and more creatures to appear. The Horde has many types of species in its ranks but there are a few critical ones necessary in the spreading of darkness.These creatures basically capture and envelope the light so that there is room for the dark. Most cannot exist in the light for more than a minute. Creatures that are defeated by anything from the world of light, release what is called Shadow Essence. The Shadow Essence is primarily used for closing rifts but may be used for other purposes. Shadow Essence is very harmful to those from the world of light if they touch it. So the Rift Sealers have created a device known as the Essence Collector which allows Rift Sealers to safely capture and store any Essence they may need to close the Rifts.