End of World? I've Got an Army

The Red Moon came down and monsters woke across the world. Human civilization broke, and the survivors built camps inside what was left of the cities. Some people found they could tame the monsters and bind a spirit beast to themselves by contract, and a tamer's strength was set by the potential of the beast he held. Strong tamers were fought over by the powers that remained. Nobody knew where the Red Moon or the monsters had come from, and there was talk of an ancient secret in the Abandoned Zone that had drawn many fighters there and buried them. Xaden had no talent for it. His family threw him out and the woman he loved betrayed him. With nothing left, he awakened the Spiritual Beast Supplier System, which gave him beasts that could grow without limit. With a single Slime he killed a Troll in front of the army. After that he built a base and trained beasts there. His family moved against him and he crushed them, then went up against the Noble Family Alliance blow for blow. In the wasteland he killed assassins, broke into the forbidden zone, and took divine beasts out of it, among them an Immortal Skeleton and a winged eagle king. He seized the crystal stones marked with divine patterns and broke up a blood sacrifice. By then the beasts under his command numbered in the tens of thousands.