The city's defenses are no longer what they used to be, and the inner and outer cities are densely packed. Coupled with the full performance of thousands of elven archers, Jia Zhengjin also used his newly learned skills to desperately swallow potions and use explosive arrows to brush wildly.

Later, kobold crossbowmen joined the battle with a team of young new crossbowmen led by Amber.

The fierce battle lasted until around 0:00 in the middle of the night, and finally won the final victory after leaving behind a mountain of terrifying giant insect corpses in the inner and outer cities!

Although there are still a few giant insects that appear occasionally, they are no longer enough to break through the defenses of the arrow tower and threaten the inhabitants of the city!

Almost everyone involved in this battle was tired and almost weak. However, because it was a long-range battle, there were no casualties except for a relatively unlucky town guard who was smashed in the foot by the corpse of a giant insect falling from the sky. This is also a great blessing in misfortune!

Jia Zhengjin's hand was so tired that he couldn't lift it, and he couldn't remember how many arrows he shot in total!

I only know that tonight's battle made him directly upgrade from level 12 to level 13!

You must know that upgrading from level 12 to level 13 will cost more than 200,000 experience points. Even if I went to Tansandia City before, plus I hunted some magical beasts after I came back. In fact, almost all of these 20 levels of experience were contributed by this wave of terrifying insect tides!

The only pity is that no boss appears. And the corpse of the insect can not find any loot other than being able to decompose into insect shells, insect wings, and a large amount of raw meat.

The newly acquired skill points are added to the power system after careful consideration.

After learning the knowledge of the power system, you can unlock the most basic thermal power generator set production. Upgrading this skill unlocks other forms of generator sets such as hydropower, wind power, solar power, and even nuclear power.

Although Jia Zhengjin already has a magic core battery, after all, the magic core is obtained by hunting demonic beasts. How difficult it is to find an electric system of Warcraft, Jia Zhengjin is deeply aware of it.

Furthermore, the Magic Core Battery has capacity. The amount of electricity that can be maintained is also quite limited, and it is gone when it is consumed! This is a one-time thing, and it is not so cost-effective! It is okay to use it in an emergency, such as generator maintenance, and replace it when there is no electricity. Or some equipment that needs electricity, and if you can't carry a generator set, you can also use a magic core battery to drive it. For example, it is possible to build a giant battle armor in the later stage.

However, it is also quite troublesome to make a thermal power generator set, because the whole unit needs five important components: power system, control system, sound reduction system, shock absorption system, and exhaust system.

And these five systems are combined by many different parts. These parts come in smaller combinations!

Even if there is a system, it is quite a troublesome production process.

But fortunately, Jia Zhengjin is not short of materials, nor is there a shortage of manufacturing time. As long as you work hard in the factory, you will be able to make it in no time.

However, there is one problem, the operation of the power system, which drives the city's lighting system. And the lighting system can easily attract a horrible insect tide!

It's just 50 street lamps tonight, and it directly attracts a wave of insects that is enough to make Jia Zhengjin soar to the next level!

A bug has about 10 to 20 XP. In other words, about 20,000 to 30,000 giant insects were killed tonight!

It's a quick time to level up, yes!, but luckily, this wave is full of bugs with very low attack and defense. If it's a stronger insect tide, I'm afraid the city will suffer.

But I finally got the magic core battery and the generator set, can't I use it for lighting at night?

Jia Zhengjin thought about it and suddenly had an idea.

Bugs are so troublesome, and it will be dangerous to enter the city, so why not let them in?

As for the method, Jia Zhengjin thought of one.

Anyway, don't there be arrow towers in the inner and outer cities? And they will definitely continue to be built in the future, until arrow towers are erected in every corner of the inner and outer cities.

And the most troublesome thing now is that when the insect tide comes, because the number is so terrifying, the arrow tower can't completely block all their paths. A large number of insects will inevitably be put into the city, and archers will need to participate in the battle to clear them.

What if you build a protective net on the periphery and above it? It can not only intercept insects, but also allow the arrow tower to attack insects through the cracks! And you can power up the protective network and turn it into a power grid, so that the insects die faster!

Under normal circumstances, this kind of vision is difficult to realize and inevitably requires very scary human resources and sophisticated planning.

However, Jia Zhengjin, who has a game system, said that it doesn't seem to be too difficult, right?

Iron ore can be used to smelt wire in the furnace, and there is also a strong iron guardrail. He could have enclosed the outer city walls with barbed wire, and then built them over the city to form a super-large roof of barbed wire. Underneath, a sturdy iron fence encloses the entire city.

After the electricity is turned on, except for the four city gates, which can enter and exit freely, no matter what is up and down, it will be blocked!

The power grid and electric fence can isolate any flying troops from outside, making it impossible for them to enter the city! However, there is also a disadvantage that the flying units in their own city cannot enter and exit at will. If you want to bring monsters, fake dragons, or anything into the city, you can only pass through four huge gates.

Of course, if you can make the city safe, it's totally worth it!

If you really have to pull up the protective net, the power grid plus the defense of the arrow tower is enough to keep any air attack out. It can also cause some trouble to besieging enemies. Although this is part of the trap, killing insects is not an experience bonus, but safety is much more important than experience! When the time comes, all you have to do is to do some repairs to the broken iron fence and barbed wire! How simple is it? Just take a hammer and take a look!

As soon as he thought of it, Jia Zhengjin took advantage of everyone to go back to rest and sleep, and worked hard all night in the factory, first manufacturing all the complex parts for making the generator set, and then taking them to the tool table to start assembly.

As for the furnace, the smelting of the barbed wire began.

By the time he had successfully assembled a complete thermal power set, there was already quite a bit of barbed wire in the furnace. He immediately took them out and hurried out to install them.

There is no way to do the iron guardrail for the time being, because there are too many iron ores required, and the resources can't keep up. Need to wait for news from the mine!

He first built four towering pillars in each of the four directions of the inner city. The pillars are made of wood, but they are not sturdy. Then, with the pillars as support, barbed wire was installed flat in all directions, creating a barbed wire roof over the city.

Of course, the whole process was borrowed from Buddy's flying monster Kuru, otherwise who could build it at such a high place?