Running through the cave and marvelling at the crystals that emitted mana, Rino came to understand a few things. Each crystal emitted a different kind of mana. While mana had no elements, these crystals emitted mana as a form of by-product as if it were a plant. It sucked up elements that it grew on to produce mana.

The green turquoise crystal lived on moss that Rino backtracked to confirm. Apart from that turquoise crystal, Rino found several other crystals that fed on different things. Some fed on the rocks and soil in the cave, while others grew in water. 

However, there was one red crystal that Rino found and what it fed on bothered him.

"Master, the carcasses are fresh."

Rino nodded. Indeed, these monsters were still bleeding, and the blood that seeped into the pit where the red crystal grew glowed warmly, pulsing quickly as if it were excited. The pile of corpses and bones in the pit that the red crystal grew in was very disturbing. It was not a recent activity, and someone was feeding this magic crystal blood on purpose to grow it.

"We should leave for now," Rino told his loyal summon. There was no use in disturbing a sleeping lion.

They walked for several hours, and Rino did not know how long they were lingering in this cave that felt more like a maze underground. There were monster trails all over the place, even if some of the cave dwellers scuttled out of their way as Rino and Mutt approached.

At least now, Mutt smelled water and fresh air in the cave, indicating that they should be heading nearer to an exit.

Things were never as smooth as Rino wanted them to be, and the magician found himself facing off with his very first enemy.

Mutt growled protectively, but Rino observed the surroundings in the dim light as he held the glowing crystal in his hand. His hound was too big to be fighting in such an enclosed area. If he went crazy, the roof would collapse on them, and Rino did not want to be buried again. The taste of dirt from his memory made the lich blanch. It was a horrible experience that Rino would rather not repeat.

The monster before them was a very fat and blind worm with thousands of spiked teeth in its mouth, threatening to grind them to dust if it ever got hold of them. Rino did not like the idea of those teeth threatening to poke holes into his enchanted clothing. He had no idea where such a big worm came from, but he hoped that this huge worm didn't like bones the way the six-armed monkeys did.

"Mutt, get back in my shadow. You're in the way."

The crude comment made the wolf whimper in shock at his master's mean command, but an order was an order. Sadly, the hound obeyed, and Rino suddenly felt like there was a lot more room in the dark cave.

The worm monster wasn't willing to let Rino go even if he was only a bag of bones and not a tasty treat without his fat mount. The lich did not let this discourage him. After all, this worm looked like a very lovely bait that the deadly river fishes would chew up. Instead of spending half a day digging for worms, he could kill this fat boy here and solve his future problems when he had the time to fish during this vacation.

The fight was concluded without much fuss, although Rino hated the smell of the worm's blood as it oozed all over the cave floor. Thankfully, his clothes were protected from potential grime, even if the same could not be said about his exposed bones as Rino cleaned the goo from his cheekbone.

The discovery of such a large monster in the cave made Rino wonder if he stumbled upon something more than just a cave. He did not think this bald worm was capable of dragging carcasses to the red crystal. Something more sinister and crafty was at work behind the scenes and suddenly, uncovering the mystery was more important than finding a way out. He hoped this detour would not eat too much into his vacation time.

Turning back, Rino retraced all the monster trails they ignored along the way. The cave had many branches, and Rino chose the trail with the least amount of disturbance. Ordinarily, the lesser the trail was used, the more dangerous the threat. It was the law of survival, and Rino wanted to know if this cave had more secrets than these mana-emitting crystals.

His efforts paid off when Rino found what he was looking for. Compared to the other areas in the cave, this place was better lit, and Rino rejoiced at the sight of many small growing mana crystals. However, something else caught his eye in this cavern with multiple split paths.

The ground was solid, and the air was generally fresher. These mana crystals did not have colours even if they emitted mana. They were mostly transparent in colour, but Rino soon realised that not all these crystals were the same as what he thought they were.

Honestly, he did not think he would find them in this world in such a manner. Since the start of his new life, Rino always wondered why the gods did not point him to a mine with ores. Now, he understood a little better.

Some of those crystals were gemstones. Rino might not be an expert in identifying gems, but he had experience knowing what kind of gems they were when he needed to craft magical apparatuses. Most of these exposed gems in the cave walls were low-grade gems. Still, their existence gave Rino some hope. If he could refine them, these gems would open up many new possibilities.

In addition, Rino saw some peculiar rocks embedded in the wall. In his previous life, he was given many mine tours by the dwarves. Hence, he could identify the most common mineral that they mined easily - iron.

He found iron!

Excited, Rino failed to register a dangerous presence watching him until they struck his head.

One moment, Rino was marvelling at the wonders of this resourceful cave and the next, he was viewing his decapitated body glowing in purple flames at the neck. Behind his body was a creature he did not think existed.

Rino cursed silently. He'd walked right into a dungeon full of monsters. No wonder this cave was full of resources! Even in his previous world, precious minerals, gems and rocks were guarded by dungeon guardians. He should have known when he saw those carcasses.