This is what happens when you put a chemical that makes zombies eat each other in an infected zone of 100 or more zombies!! The Zombies attacked and ate each other, but there was one particulary strong zombie that was (apparently) cannibalistic (before the infection) that would not stop eating the other zombies around him. Then the UNTIHNKABLE happened! the virus had mutated with the other viruses inside this crazed zombie. It grew 10 times it's size, turned purple and gained incredible stregnth! the Devourer was born.
The devourer is a boss zombie that is typically encountered at lv 46 and up. Like all boss zombies before it, they are very hard if you are not prepared. The first time you fight one is whern you are in the lower lv 40s and from then on you have a chance of recieving some fame. He's Tough. To be fully prepared, make sure you have upgraded your better weapons to max class and have a reserve of health packs. As the story progresses, they will get easier. Be prepared! Devourers get hungry very quickly, so don't expect them to be gone for too long...
Credit Goes to PSC Player Chaos Dracos for the picture and the description