As for the specific upgrade conditions, of course it is determined by the number of enemies killed, and this is still caused by accidental manslaughter. After all, Xie Zhi's layout is to get more subordinate zombies, and does not emphasize the effect of killing enemies.

Job fairs, you can't even kill all the applicants.

But after a real fight, the fighting plants can't be specifically commanded. They follow a fully automatic operation mechanism, which can ensure that most of the disabled zombies are left. This is because

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