After saying that, Xu Feng took the big bag of materials and quickly entered the secret realm he carried with him.

Xu Feng walked quickly to the alchemy furnace in Yizhuang and put the five materials into the furnace one by one.

"Unfortunately, without any special alchemy tools, I can only make do with this alchemy furnace..." Xu Feng said to himself.

Whether it is alchemy or alchemy, the processing of materials is nothing more than refining and extraction. The subsequent refining has its own techniques. Xu Feng does not have alchemy tools, so he can only make do with the alchemy furnace. The spiritual-level alchemy furnace has no problem processing some mineral materials. After all, the raw materials of some elixirs also include minerals, metals and the like.

The flames were blazing, and the five kinds of mineral materials in the alchemy furnace began to change slowly under the burning of the fire. The original pile of powder began to melt slowly and gradually became viscous. The impurities slowly separated and flowed out from the diversion port of the alchemy furnace. These were impurities. If they were not cleaned up, they would cause alchemy poisoning during the alchemy process and reduce the quality of the elixir!

Soon, all five portions of ore materials were extracted and refined, two of which were still in powder form, and the other three turned into viscous liquids.

After taking out the five refined materials from the alchemy furnace, Xu Feng's figure flashed and disappeared on the spot.

"The materials have been refined. All that's left is to mix them together and let a mechanical creature swallow them first!" Xu Feng began to mix the five refined materials.

"Unfortunately, if we know alchemy, we can make real rust poison. The current one is not even worthy of the alchemist's attention. The rust effect is not even one-tenth of the original one. However, the core principles are similar, but the effect time may be longer..." Xu Feng explained while making it.

Soon, a dose of rust poison was produced by Xu Feng. Xu Feng was not sure about the effect of this simplified version of rust poison, so he could only give it a try.

After catching the two mechanical fish that Shui Sheng and Zhang Zibing had caught earlier, Xu Feng poured the rust poison he had just made into their mouths little by little. Then he threw the two mechanical fish into the upper reaches of the river. All that was left was to wait patiently.

One minute, ten minutes, half an hour, one hour...

Time passed little by little, but there was no sign of anything unusual in the river. There were less than two hours left before the main mission was completed.

Shui Sheng secretly glanced at Xu Feng and sighed in her heart. It seemed that this promotion mission would fail.

"What kind of rust poison is this? It doesn't sound very reliable..." Shui Sheng muttered softly.

At the same time, the two mechanical fish in the river began to emit gray-brown powder particles and their movements became distorted the moment Xu Feng threw them back into the river.

Any mechanical creature infected by the rust poison will become a source of poison, and its body will become the nutrient of the rust poison. As its body is corroded step by step, the rust poison on its body will slowly dissipate, looking for nearby mechanical life, contaminating, corroding, and decomposing...

The poison of rust is like a fire in the forest. Once it starts burning, it will be unstoppable until it destroys the entire forest.

However, the rust poison made by Xu Feng was not the authentic rust poison. If it was the rust poison made by the alchemist, only one drop would be enough to kill all the mechanical life in the river in a short period of time.

The two mechanical fish that had swallowed the rust poison persisted for more than half an hour before finally turning into a ball of rust and sinking to the bottom of the river. At the same time, the rust poison dissipated, causing more than a dozen mechanical life forms around them to be infected with this poison.

These mechanical life forms, which were infected with rust poison on their body surfaces, rusted at a slower rate. Standing on the river bank, nothing unusual could be seen, but inside the river, these mechanical life forms had already become a panicked group.

The poison of rust is like a thorn in the tarsal bone. Once it gets contaminated, it will rust completely from point to surface, unless the entire contaminated area is dug out, but the mechanical creatures in the river cannot do that.

An hour later, all the mechanical creatures in the entire river were infected with the rust poison, and more and more rust poison gathered around the invisible light curtain around the space transmission node, constantly corroding the light curtain's defense.

After waiting for more than half an hour, Shui Sheng became a little impatient.

"Is your rust poison really useful? Otherwise, let's try to sneak in in stealth and attack with all our strength. Maybe we can break through the defense of the space transmission node..." Shui Sheng's face was full of anxiety and worry.

"It's useless. Why do you think there are so many mechanical creatures here?" Xu Feng shook his head and said, "The invisibility talisman can only hide our bodies, but not our temperature and smell. Once we go in, those mechanical creatures will be able to detect us easily!"

"If you don't believe me, ask Zhang Zibing if they have this method?" Xu Feng shrugged and said.

Shui Sheng turned her head and looked at Zhang Zibing. Zhang Zibing sighed, nodded and said, "These are the most basic means of detection. Every mechanical creature has them. Not only that, even illusions are useless to them. They can detect all illusions..."

"Then we will now..."

Before Shui Sheng finished speaking, Xu Feng stood up and looked towards the river not far away, with a look of joy on his face.

There is no wrong version in the 1619 book forum!

The simplified version of rust poison refined by Xu Feng is actually something that almost every apostle of the secret realm in his previous life knows. Whenever they encounter mechanical creatures that they cannot deal with, they will refine some to reduce the difficulty of attack. The disadvantage is that the toxicity is weak and the effect is slow, but it is useful, so Xu Feng is still very confident.

"Look, the rust poison is taking effect!" Xu Feng shouted, pointing at the river surface.

At this time, a gray-brown trace floated on the rolling river surface. The gray-brown color became thicker and larger, and soon covered a large area. As the river continued to flow downstream, the entire river was covered in gray-brown.

It took more than half an hour from the appearance of the gray-brown color to the entire river being covered in gray-brown color, and there was less than an hour left until the end of the main mission.

"Shui Sheng, go look in the river again!" Xu Feng shouted.

Shui Sheng also showed a look of joy on her face. She quickly took out a paper talisman, folded it a few times, and threw it casually. It turned into a bird and rushed towards the river.

Soon, the bird turned into a small fish and fell into the river. The scene in the river suddenly appeared clearly in Shui Sheng and Xu Feng's minds.

…

(End of this chapter)