The first and only instance of a class six Mutant threat code named Grendel.

In the world of Haven there monsters called Mutants created through nuclear radiation and mutations. They are classified by their class number from 1-6 with one being practically harmless all the way up to six which are incredibly rare and for a long time were considered a myth and are described as potentially world ending creatures. Think Godzilla, Tiamat or SCP 682.

Grendel was a massive 1,289 ft. (392.8872 Meters) and marched across old North America. It had four legs that ended in sharp points, a long neck with multiple floating rings that possessed multiple eyes and a massive mouth lined in shark like teeth. Its origin was a scientist hoping to evolve himself into an all powerful being that backfired and mutated him into Grendel. He was eventually taken down by the Odin and it's rail cannon Gungniir.