20 Monster Furnace

Art sat on the hill, resting and regaining any mana that was consumed along the way. After 30 minutes, Virion returned and lead Art to the location of the rat's nest.

It wasn't very far, as it only took a 2-minute jog for them to reach the river. From a not too far distance away they could see an ominous looking hole digging deep into a mound near the river.

Unlike the cave the snakes used, this is very much unnatural and was clearly dug. Even from their distance away Art could smell the putrid stench wafting from the hole.

The rider near the hole was also contaminated, with a black sludge built up along the bank and the river having a blacky green colour to it, instead of the normal crystal-clear water.

Luckily for the village, the nest is set up downstream to where they pull water for irrigation and drinking. So, this contamination doesn't cause them any harm but anything further downstream is likely suffering.

Virion once again gave Art an overview of what's going to happen and then swiftly jumped out towards the rat nest. Art shortly followed behind after safely securing his bag filled with the snake eggs to the top of a tree and hidden by leaves.

When Art reached the entrance, Virion was already gone and painful shrieks could be heard echoing from below. Since Art had a little prep time before the first set of rats run out, he set up something similar to what he did at the snake cave.

Blocking off the entrance and making sure it can withstand the rat's impact. Unlike what he did with the snakes he didn't leave a hole for them to get out, instead only a tiny hole for him to send his magic through.

A solid rock wall should be more than enough to block the rats, since unlike the snakes the rats have super weak defence, and mostly rely on their speed and sharp claws. Since rock is resistance to sharp attacks, they will be practically unable to do anything against it.

As he was setting up the wall, Art suddenly thought something crucial. 'Wait, this is a trial. Training set up by master. Killing a few thousand rats would be pretty easy since I can just use a few large scales magics but its not a few thousand but likely close to the 10,000-master said there would be.

Even with my large mana pool, I wouldn't be able to kill them all with just magic attacks. The first training was the snakes, which should have been training for killing. This one however seems to be stamina and strategy training.

Okay, lets change the way I think about this. A wall like this would hold and I can just shoot some fire spells into the group, but that would eat away at my mana quite quick, considering only a certain amount can fit into a space at once.

I need to be more efficient and conserve my mana more. How about I create two walls. One on the outside and one inside, with a gap between them. On the inner wall I keep a small hole for rats to funnel in through, while on the outer wall I keep two very small holes for me to channel magic through.

If I keep up a weak flame, then on the other side I input the occasional wind stream then I could create a kind of furnace within the middle of the two walls. Since a weak stream of fire consumes near no mana and a medium strength wind stream would only consume a little at a time, that should create enough fire power when combined to kill all the rats that enter without wasting much mana.

I will need to control the strength though; I can't have it getting too hot in case it destroys the rock but it can't be too weak that it doesn't kill them fast enough. Let's create a third hole on the outside which I can use to funnel excess heat should it get too hot.

Okay, I need to get this set up quick. The rats should not be too far away.'

Art changes his plan and alters the outside wall to have 3 small holes. Then on the inside he creates another wall with a door, and then a spherical room between them which will contain the fire.

Hearing noises getting closer, Art decides it start it up. Creating a small trail of flames from his left hand, he places it up against one of the holes and allows the stream of fire to enter the middle room.

On the other hand, he creates a similar strength wind stream which he starts to control to create a whirlpool. He starts out slow, so as to not put out the fire and as the fire started to increase in strength, he increased the amount of wind.

In only 30 seconds, Art had created a pseudo-forge hot enough to melt metal. With the wind mostly enclosed and spinning at a fast rate, the heat generated was very intense. He also didn't need to add as much wind now, so his mana consumption dropped slightly and used only enough to keep it at this temperature.

Even while on the other side of the wall, Art could feel the intense heat radiating from within. Worried it's a little too high, he guided some of the flames outside.

It was a good job he did that, as because on the inside the rock was glowing red and was as radiant as the sun. But now due to the excess being taken out, the rocks colour died a little and turned to a weak red colour, which should be enough to prevent it from melting or being destroyed.

At first Art kept it up for over a minute, wondering where the rats are at. He couldn't heat anything, just the sound of the river and the wind. He started to worry he set it up too early and he should stop so as to not waste his mana, but decided that since he started, he should just keep it up and deal with that he might have miss timed it.

Unknowingly to Art however, he didn't start it too late. The inside of the rock was littered with ash as it combined into the flow of the wind. Black streaks funnelled into the intense heat, but after only a few steps they combusted and disintegrated leaving tiny bones. Only a few seconds later even the bones where gone, being wafted into the whirlpool as dust.

The wind and flames unknowingly silenced any noise the rats could make. Completely preventing it from ever reaching Art's ears. This was both bad and good for Art, good because it shows how effective his plan is but bad because he now no longer knows the status of the rat's numbers.

10 minutes swiftly passed by and Art felt at least a quarter of his mana had been drained. By now Art had already guessed that the furnace he created blocked all noise from the inside. Unfortunately, he had to start increasing the amount of wind he has to use, as when he started to funnel out some flames after it got a bit too hot, he noticed a lot of minuscule particles of dust.

He saw that they slowly started to cover the flames, making it require more mana to counter it. So now he must keep a steady flow of dust filled flames coming out and a slightly higher supply of wind to keep up with it.

He didn't know how many rats had died and could only keep going and stop when his mana was at a certain point. He had already decided to stop when his mana reached only a quarter left, so he can have some in case he needs to still fight.

What Art didn't take into account and over looked was that the dust swirling around would not only affect the flames but also erode the rock slowly and over time.

It was only after a further 10 minutes had passed did Art notice that he is feeling the rocks in front of him become hotter. It was then that he thought about the rock erosion, and cursed at his stupidity.

'Damn I forgot about the rats bone dust being able to erode the rock walls. Fuck. I can't fix it either, as I am already at my dual casting limit of constantly supplying wind and fire, I can't just separate my concentration and also reinforce the stone walls.

Fuck what can I do. If this keeps up then the rock walls will collapse, allowing the rats to escape, but also it would be incredibly dangerous for me. The intense heat inside here would spill out and roast me in seconds.

The only solution is to spend more mana though and funnel more flames out. That's bad though, as I have already used over half my mana and am nearing two thirds used.

I also don't know how many rats are left, they could all be dead or this entire time after the first batch they have been staying away. I think at this point I should stop this method; I can't keep using this mana without knowing how many are left or when this rock wall will reach its limit.

The residual heat should keep up for a little while and continue harming rats, but once it's done, I will have to attack head on, on any remaining rats.'

Stopping the supply of wind and flames, the inside flames died down quickly. The lack of winds supporting it and the bone dust smothering them, only a minute later the flames stopped completely and the bone dust has settled on the floor.

The residual heat however kept on doing work, as the stones where still red hot for a further 5 minutes before it reached the point that Art could no longer feel the heat through the wall or from the holes.

He had already during the past 6 minutes regained a little mana, bringing up back up to over half and created a few new walls enclosing him and the entrance. He made a larger hole on the first wall, and used wind magic to suck out the heat to the outside.

When the heat being safe enough for him to enter, he demolished the wall manually and had an, Area of Effect spell ready. He didn't hear any sounds so he doesn't think there are any rats but he would rather be careful and have the spell ready.

After the wall was demolished Art saw no rats and instead just a thick pile of dust sitting at the bottom. Heat assaulted his face as the rocks where still releasing the heat energy. Although uncomfortable and making his entire body sweat intensely, it was deal able for him.

Treading across the dust remains, art demolished the other wall and was now able to head straight into the nest. There were still no rats in sight however, so he was now somewhat sure that they all died in his monster furnace.

He didn't enter the nest and still remained at the entrance, fulfilling his duty of protecting it. He was a little worried that some rats may have escaped through digging a new tunnel, but he isn't omnipotent and can't just know if they did that, where they did it and safely say he can cover both exits.

So, he just stood there with an attack ready, waiting for Virion to finish up on his end. Obviously, he didn't just stand there, he gathered and regained his mana but also stored away all the remains of the rats. He doesn't know if rat ash would be useful, but the sheer quantity might make it valuable in the future.