Anomalies: Because Yggdrasil breaks about a rift in the world wherever it goes, creatures called Anomalies sprout out from nothingness and into existence. These creatures, like their creator, seem to have no real mindset or clear goal, instead assisting Yggdrasil in "judging" all other life and pillaging to the Central Regions, much like Yggdrasil. These soldiers usually take the form of armored knights or creatures from legends long past. They carry with them a wide arsenal of magic and technology combinations, and come in all sorts of various shapes and sizes. However, they are not immortal and can be slain.
*With the Anomalies, anyone can create and control their own to add to the story. All Anomalies will be accepted, provided they can be defeated in some way. This is mainly cause I'm too lazy to create a whole batch of creatures myself. With that said, I highly encourage you guys to make and implement your own Anomaly. The one featured above is an example of an Anomaly Scout.*