Infinite farming Savior

[World: the end of the zombie] [mainline task 1: protect important characters from death] [mainline task 2: kill 1000 zombies] [mainline task 3: obtain 10 evolutionary crystals] [intimate tip: the faster the task is completed, the more rewards...] "what, there is no time limit? Wait for 10 years to farm!" this is what a farming enthusiast said then he found that he had unknowingly become the Savior of countless worlds World Order: Zombie Apocalypse