Those two guys put the marble in a special container made of iron because whenever they touched something flammable, it would emit heat and burn. Thanks to that, Billy wondered if they could be used as weapons. It would be quite something if they exploded upon contact, or at least made massive waves of flames to spread around when they were thrown with enough power. Apparently, neither of those as possible, but Billy was quite sure that he could fiddle with it and then use it in other ways. In any case, the number of materials and the diversity that one could find across the dungeons of that world was pretty high, and Billy never heard of two identical dungeons...
Regardless, while those monsters emitted some water since the heat was like really hot air, Billy was having a hard time cooking down. If it weren't for Spiritual Core, using that tactic wouldn't work. It would consume too much mana… Still, Billy kept using that even though it wasn't efficient, and the helpers couldn't help but frown, imagining how he could make it in such a place. Those who got hit by the fire spirits were left with some nasty burn marks. So, it was clear that the level of his magic was insane.
"I suppose I don't need to continue the tunnel today, but I should learn some way to stock my magic… spiritual core is letting me recover a lot of mana, but there is my limit," Billy thought.
Storing his mana wasn't difficult. The engine of his magic cart could do that, but Billy couldn't take it back. Putting that aside, Billy began to fight the monsters seriously since he could think about those things later. Thanks to that, he ended up killing almost 250 monsters in just two hours since they spawned every minute, and at the beginning of the dungeon, they always appeared in groups of two.
"Do you guys know how much these cost?" Billy asked.
Valentin bought two every week, so it seemed that they could last for seven days after they began to be used, and while Billy was the one paying for them, Kate was the one who looked after the expenses of the house. She and Valentin were the ones who knew the price of those things.
"They cost ten cooper coins each, sir,"
They were pretty cheap… So, Billy obtained something like 25 silver coins. The helpers needed a payment of one silver coin per hour, so he only got 21 silver coins. It seemed like a small amount, but money was money, and Billy wasn't there to make a killing anyway. He made his Water Transformation level three times, so he got a bit better at it, and that was enough.
In a hurry, Billy went home, only to see that his wives were still sleeping. It was just three in the afternoon, so it seemed that Billy got worried for no reason.
"Inside the tunnel, the tires don't need the spikes, so maybe I should change the material for something softer. It will lose durability, but it is fine," Billy thought. "Closing the car with windows and a ceiling might also make the trip more comfortable… But maybe I shouldn't bring the idea to those two that they might come with me to the dungeon town. They might insist on exploring the dungeon as well."
Billy went to clean himself since he sweated quite a bit inside the dungeon, and while he was in the bath, he wondered what he should do about the problem of storing his mana somewhere else. If he could do that, his battles would become extremely easy, and his work inside the tunnels also would become more straightforward. The idea to use his level-up status only to magic and become physically stronger by training was too simplistic and wouldn't solve the problem…
As soon as he had the chance, Billy went to make some rings using dirt and then transformed them into iron while keeping in mind the image of what he wanted. Naturally, things didn't go the way he wanted. With his image, the ring only gained the effect of adding a few mana points to him. Billy checked the skill shop, but he didn't find anything that could help him either… And he had yet to find a way to learn alchemy.
Sending his mana to an object seemed a bit difficult if the plan was to take it back, but what if Billy could make his mana move to a place on his body where it could be accumulated in vast amounts, and then he could use it when he wanted? After recalling an old anime, he had the idea that some individuals used that tactic to suddenly gain a boost in power and energy when they needed it. However, it was necessary to have extreme control over their energy…
Billy wondered how he should try that, where should he gather his mana? His hand? His head? His heart? He only made them slightly sturdier when he did that, like he had temporarily increased their defense. When he did it with his hand, he increased his strength for a short while, then the energy dissipated.
When Billy tried to transfer his mana to the spiritual core, he only made the skill gain more experience… Maybe he was missing something, but he couldn't tell what it was. After thinking for a while, he decided to send his mana to his back. Instead of covering the skin like Fierce Aura, Billy focused more mana a bit above and on a single spot. It worked, he could feel his mana being used and moved to outside him, but it still was under his control. But when he felt satisfied, he relaxed, and the energy dissipated.
"Oh, crap… Does this mean that I need to keep the energy under control all the time?" Billy asked. "I don't think I will be able to keep large amounts of mana stored while I sleep…"