What is the use of nuclear explosion of rpgk city bookstore skill book?

You can increase the attack power, defense power and other attributes and gain new skills. K city entry method:

1, talk to the store, and the boss will ask you to send a batch of goods to K City, and you can pick up the task by choosing a transaction.

2. Then go to the gate of K City and tell the guard. Guards were not allowed to enter at first. You can convince them with the boss's task.

3, so the doorman will open the door for you, but you need to pay a fee. After choosing to pay, you can enter K City.