After each zombie mutates, a mutation crystal will form at the center of its eyebrows, and these mutant crystals will also upgrade as their strength continues to improve. Similarly, these mutant crystals can also be absorbed by other mutants to increase their own level, which is also the main means of leveling up the ability.

Chu Feng was mainly searching for materials just now, and now that the materials have been collected, the zombies that he solved just now naturally can't be left behind.

Chu Feng took down the military shovel from behind him, and then took out five mutant crystals from the heads of these zombies.

If you want to upgrade to a first-order mutant, you must take ten first-order mutant crystals or one second-order mutant crystal, and if you want to upgrade to a second-order mutant, you must also take ten second-order mutant crystals or one hundred first-order mutant crystals. If you want to upgrade to a third-order mutant, you need ten third-order mutant crystals, or one hundred second-order mutant crystals, and first-order mutant crystals are invalid. By analogy, if you want to upgrade to the corresponding level, only mutant crystals of the same level or ten times lower order will have effect, and mutant crystals that are two levels lower than the mutant level will not be effective for the mutant to upgrade.

In addition, if you get a mutant crystal that is two or more orders higher than your own level, the mutant can also absorb it, but you can't swallow it directly. If you forcibly swallow it, you will not be able to withstand the huge energy of the mutant crystal and explode to death. After the mutant reaches the third order, he can directly put the mutant crystal in the palm of his hand to absorb it, or swallow it.

Neither Chu Feng nor Li Jun had been upgraded yet, and Chu Feng was almost certain that at this moment, apart from him, it was impossible for anyone else in this world to know about the existence and utility of the mutant crystal. As for the effect of the mutant crystal, it will not be revealed on a large scale on the Internet until three days later. That is, after three days, all the power systems in the world will not work, and the network will naturally not be able to use.

Chu Feng moved more than a dozen boxes of ham sausages and bread, stuffed the big G to the brim, and then drove away satisfied.

Along the way, Chu Feng killed zombies as he walked, and soon obtained twenty-three first-level mutant crystals.

Finding an empty and uninhabited place, Chu Feng first closed the car door, then took out a bottle of mineral water to wash the ten mutant crystals, and then stuffed them all into his mouth.

This feeling of swallowing mutant crystals felt familiar for a long time, but what surprised Chu Feng was that he had already swallowed ten first-level mutant crystals, but he didn't have the expected feeling of upgrading at all.

Chu Feng gritted his teeth and washed ten more. It's just that after swallowing the other ten, there is still no feeling of upgrading. After thinking about it carefully, could it be that because I swallowed two ability fruits, the mutation crystals needed to level up were also multiplied? It's just that it takes a few times the mutation crystal, and it can't be determined.

Since he couldn't be sure, Chu Feng no longer continued to waste mutant crystals, but continued to hurry back.

Along the way, Chu Feng dealt with seven more lone zombies, and after obtaining seven first-level mutant crystals, he had already rushed back to the suburban villa.

Naturally, there were zombies in the villa area, and Li Jun listened to Chu Feng's words and did not go out.

When they sent all the supplies in the car to the room, two zombies with short eyes chased after them, and Chu Feng took two electric batons to directly eliminate the two zombies.

"Electric batons? Where did you get it! Li Jun was a little excited when he saw the electric baton in Chu Feng's hand.

Chu Feng glanced at Li Jun, this guy's focus is always different from normal people, now is the time to care about electric batons!

Li Jun's parents were also frightened when they saw the appearance of the zombie just now.

Chu Feng briefly introduced the situation outside to them, and when they learned that such zombies were almost everywhere, and once they were bitten or injured, they would become the same as them, their faces were even more ugly.

Chu Feng took Li Jun to his room and carefully took out the ten mutant crystals he had accumulated.

"What is this?" Li Jun took the mutant crystal in his hand and looked at it repeatedly.

When Chu Feng explained to Li Jun that this was dug out from the eyebrows of zombies, Li Jun's hands were also trembling.

"You're not kidding me?" Li Jun asked again.

Chu Feng nodded heavily, and at the same time asked Li Jun to swallow all of these first-order mutant crystals.

Li Jun suddenly stopped, with an expression of disgust or disgust on his face.

Chu Feng asked Li Jun to feel the energy crystal in his eyebrows, and then told him some of his 'conjectures', such as absorbing the energy crystal of the zombie can improve the ability of the two, and so on, Li Jun also gritted his teeth and swallowed the mutant crystal directly.

Chu Feng looked like he was waiting for the battle, he originally thought that Li Jun would be able to advance, but after looking at it for a while, Li Jun didn't seem to feel the slightest feeling.

Having the experience of leveling up in his previous life, Chu Feng knew very clearly that every time he raised his level, it would be accompanied by a burst of physical and mental pain, although it was not long, but ordinary people were unbearable.

What's more, Li Jun is still preparing to break through for the first time, and when he is caught off guard, it is impossible to endure the pain without shouting.

Li Jun and Chu Feng looked at each other, and they didn't know what happened to each other for a while.

"Don't you feel anything?" Chu Feng finally couldn't help it, and asked out loud first.

Li Jun shook his head.

At this time, Chu Feng's brows furrowed even deeper, and neither he nor Li Jun could advance smoothly, could it be because of the changes brought about after swallowing the complete plant.

"I also swallowed some mutant crystals on the way back just now, I can clearly feel the changes in my body, if we take more mutant crystals, it should make us stronger!" Chu Feng didn't completely reveal the secret of the mutant crystal to Li Jun, after all, it was not easy to explain to him why he knew so much.

If you want to tell Li Jun that he was reborn, regardless of whether Li Junxiang believes it or not, once this news leaks out, it will bring huge trouble to Chu Feng.

Li Jun didn't doubt Chu Feng's words, not to mention, there were indeed some zombies in the villa area at this time, and no one wanted to be surrounded by such dangerous things. But just when Chu Feng and Li Jun were about to go out and do something to the zombies, Li Jun's parents came out to stop the two of them at this time, only saying that they wanted them to wait for rescue and didn't want the two of them to take risks.

In the eyes of ordinary people, since such a disaster has occurred, the state will definitely send people to the rescue. All they have to do is hide in their homes, and once help arrives, they will be saved.

In order not to worry the two elders, Chu Feng had no choice but to dispel the idea of going out to deal with the zombies immediately.

Chu Feng couldn't explain to them that from today onwards, the rules they had followed before had completely constrained this world at this time.