Living caves, Rino learned, were caves with ores and minerals. They were constantly growing for some reason, and every living cave had a complete ecosystem, home to monsters. Each living cave had a powerful monster that ruled over this society of monsters called a guardian.

That would explain a lot, and Rino finally understood where he went wrong back in the jungle. That womanticore was the guardian of the cave. One did not simply walk right into the guardian's lair and expect to escape unharmed. Miners did not visit living caves because it was simply too dangerous. Normally, villagers would leave the living caves alone and protect the peace of their village. They would send sacrifices for the monsters at the cave's entrance as an offering for peace. More dangerous monsters do not leave the caves. They were more or less bound to the cave and their treasures.

Living caves reward their guardians well by producing various minerals to the guardian's liking. In the case of the womanticore, the living cave produced mana crystals. In the case of this ravine living cave, Acht theorised that the guardian preferred something strong and was most likely a combat boss, much like the sabre tooth wolf.

Rino hummed. He could deal with a combat guardian better than a mythical boss like the womanticore, who had both physical and magical abilities.

Once he understood the ecology of living caves a little better, Rino started to see signs of it within the cave. The markings on the walls that he thought were regular rock fissures were actually not the creation of nature or water. They were monster trails left behind as a marking of territory, much like the footprints back in the other cave.

There were all types of monsters, but Acht was right about this living cave liking combat monsters a little more than the magic type. There were different classes of monsters, and the bats they saw at the mouth of this cave, at the ravine by the stream, were known as critters, the scouts of the cave and the only ones who left the cave to source food from outside.

In a way, they were sentry guards. Rino already alerted the guardian of his presence when he woke the bats up. Now, he had bigger things to worry about while exploring their territory. He could hear the occasional fluttering of something big in the dark beyond the vision range of his fireball, and Rino slowed down. The ores in this cave appeared more frequently as Rino went deeper.

After critters, Acht explained to his master using the telepathic bond that feeders also act as ecological dumpsters. In this cave, they were the vultures that Rino did not see. Their nests could be found by the side of the ravine wall, sticking out from uncanny branches of bushes that grew into the side of the rock surface. The lich vaguely recalled seeing those nests now that Acht mentioned it. He didn't pay attention to them earlier, but he really should have. Unlike the monsters and bats, vultures weren't nocturnal.

The monsters fluttering in the dark circled Rino as he walked, admiring the huge ore pockets filled with glowing green minerals. The lich did not sense any mana coming from them, but there was a strange smell in the air. Deciding that it was better to leave this peculiar mineral alone, for now, Rino focussed on sensing the monster protectors that Acht told him were the main defence force. Their job was to kill all threats to the living cave's resources and hunt for the cave guardian.

The monster ecology system in a living cave was complicated as Acht rattled on. Food could be grown and harvested in caves, and Rino marvelled at the gigantic mushrooms he stumbled across in one of the caverns. This had to be a food farm. The mushrooms towered above Rino, and the lich backed away slowly after seeing how one of the protectors flying too close to him collapsed onto the ground and sizzled when the large mushroom rained spores on it.

In a few minutes, the huge leather-winged gargoyle turned into a spore bed for new mushrooms to grow. Acht shrunk fearfully and hid behind Rino. The magician found that reaction slightly amusing. Despite turning into a powerful spectre after his death, Acht still retained some of his human instincts. It comforted Rino a little to know that human nature remained the same even in death, compared to those living dead in the village affected by the plague.

Gargoyles were low-level mythical creatures, and Rino wondered if all living cave guardians were mythical creatures. He could only guess what kind of creature the boss of this rock cave was.

"M-master!"

Rino turned around just in time to evade a swift but lethal strike. The blow landed on the cave wall behind him, and Rino hurled three fireballs in succession in the direction of the attack only to see what appeared to be the living cave's boss.

The guardian was a beautiful lady of ethereal beauty on the top half covered in green scales. Her glowing yellow iris screamed danger as she hissed, flicking her forked tongue at Rino while dodging his attacks.

The lich understood those tracks on the ground now, but he was surprised to see leathery wings behind this half woman half snake guardian. He knew what lamias were but did they usually have wings? It was absurd enough to see a half serpent beauty who could kill in cold blood with her suffocating embrace. It was more ridiculous to see such a large monster take up the space of this cavern with her huge wingspan. It wasn't as if she would be doing much flying around in this cramped cave, but Rino digressed.

He quickly dodged a venomous spit that melted a nearby iron ore rock. The lamia was fast and followed up quickly, using her tail as a spring, coiling and propelling herself in Rino's direction. Those ugly teeth glistened with venomous saliva as the lamia prepared to bite Rino.

Unsure if venom would take effect on a pile of bones like him, Rino played it safe and dodged before landing a fire-coated fist on the white underbelly of the flying snake lady.

Nothing much happened when his fist made contact. The lamia did not scream in agony. Instead, she used her hand to latch onto Rino and her tail wrapped around Rino in a deadly hug. The lich felt some of his bones shatter under the killer affection, and to his horror, the venomous saliva melted parts of his mantle that Noir gifted him.

Enraged, Rino glared at the snake lady. He was going to make her his first leather product.