2345 2E the first signs of the corruption start to appear. A cancerous disease-like substance that spreads to lifeforms and completely takes them over. Nobody knows how it started, or where for that matter, but once it appeared it was extremely hard to get rid of. It took 1200 years the first time, but it keeps popping up in places. It has been one of the greatest tragedies in the history of Mithra, only rivaled by the Mesantian plague in death toll.
Somewhere in the year 2345 during the age of unity, strange creatures started appearing along the central highland woods. They appeared to look like normal animals but deformed and reshaped. Not long after that, villages started disappearing completely. Then it was discovered. A plague that corrupted everything it got in its hold. It started with rats, then went onto dogs and wolves. In the end, humans got caught up in it. They were deformed to the point that they looked more dead than alive. The corruption had taken over their brains, making them extremely aggressive. Whole towns were quarantined and multiple failed defense lines were formed. Centuries of fighting this plague took all the recourses the empire had. This was partially the reason for its downfall. After a few hundred years, the corruption pockets that were now spread throughout Mithra started to get more coordinated. By this time the fighting became horribly bad. Every kill had to be burned or the risk of it becoming meat for the grinder that was the corruption. All sorts of creatures started to appear in the corrupted territory. Weir flesh dogs that had egg sacks hanging from their bellies. Abominations with a thousand feet, made of flesh and limbs. Insect like creatures that seemed to pop out of the flesh of corrupted individuals. Monstrously large walking beasts with thousands of eyes and even more teeth. And the scariest of all where the plague priests. They seemed normal until you got a good look at them. Their skin cold, their heads reformed into peering peepholes. Carrying lanterns, covering every battlefield, looking for anything of use to the corruption.