My monster merges everything

The apocalypse is coming, and roommates offer sacrifices to heaven.
When the fog falls, the Book of Blood Spirit appears in the hands of all survivors, and only the contracted monsters can survive.
Su Han turned his attention to the mutated and twisted roommate next door, and silently took out a shiny fruit knife...
The ferocious flesh corpse, the giant spider with cracks, the eyeball covering the city, the palm monster with one eye and sharp teeth...
Civilization has fallen, cities are broken, and all humans have become meat in the mouths of monsters. If you want to survive, there is only one way:
Use monsters against monsters