Survival in the Apocalypse Begins with Summoning the Undead

The end of the world is coming, fog covers our eyes, animals and plants mutate, and ferocious beasts and alien races attack. Su Mo's welfare system for time-travelers arrived late, but it arrived. Undead summoning system: The little skeleton is a bit lacking in calcium, the little ghost has a big fist, and the undead knight mount is not given away! Fortunately, all difficulties can be overcome. Calcium supplementation for small skeletons upgrades silver skeletons. Silver Skeleton upgrades Gold Skull. Gold Skeleton upgrades Skeleton King. Little Ghost Upgrades Lich Lich upgrades Archlich. Archlich upgrades to Lich King... The little ghost dumpling changed from a lich to a beauty. This is cheating! Others were still hiding in the house, suffering from hunger and cold, and shivering in fear. Su Mo had already led the army of skeletons he summoned to overthrow the ferocious alien race...