Apocalypse: Monsters Merge, and I Become the Greatest Monster

A man from the future who transmigrated, and a book made of human skin that appeared out of nowhere: neither has anything to do with Yan Fan. Yan Fan is a deliveryman standing by the roadside. But when he punches the time traveler to death and snatches the book of human skin, the future set in stone changes. Deer antlers + deer head + cannibal = Wendigo? Wolf claws + wolf hide + zombie core = Bloodthirsty Werewolf? Blood Eagle torture + vampire core = Spass? After awakening as a demon hunter, Yan Fan is thrilled, because he can fuse with every monster in the book!