Aiming For Maximal Volume In The Apocalypse

In the five years of the last days, the earth became purgatory. The poisonous sister in her body was killed by Warcraft, but Chen Yan had no counterattack. But when he woke up again, he found that he was reborn before the end, and he had an ability! The system came and told him how to save his sister. But the premise is that he must upgrade crazy to stop the end.