Observing the process of Core Formation gave Lan information on how a being obtains a complete mana body.

Abridged it was something like this: Organs dissipate into life mana, then said life mana helps disintegrate the heart into mana, all of which concludes in forming a Heart Core by converging said mana and absorbing surrounding mana as well.

Curiously enough, although the internal reproductive system was disintegrated as well, the external organs remained intact, perhaps still being functional in some way.

Another curious thing about the whole 'transformation', was that an animal with no initial affinity for mana, just like Remy previously, can obtain an affinity by absorbing enough elemental mana.

'...And if I'm thinking right, then it may mean uniquely evolved animals depending on the mana available in the environment.'

That thought gave Lan another idea for future Floors... Although he hasn't finished the first one yet.

However, on the topic of evolution, things got a bit confusing. Lan called both the standard animals, evolved animals, and mana-bodied animals just that, 'animals'. So, he decided to reclassify them a bit.

'Okay, then let's leave the slightly big animals just that, animals. They're not that different from the ones I've seen on Earth, just slightly bigger.'

'Then the evolved animals... Hm. With evolution they sometimes change their appearance and size greatly becoming bigger, stronger, more... Monstrous. Yes, that's it, Monsters!'

'And as for the animals with mana bodies, they could be said to be made of magic, I will probably call them Magic... Animals? Sounds lame, how about Magic... Beasts! Yeah, Magic Beasts, that's the one.'

As such, Lan classified the class system for the creatures, animals evolve into Monsters, and Monsters evolve into Magic Beasts. Plain and simple.

Being done with the brief internal monologue, which Lan had plenty since becoming a... Core, Lan got back to his domain.

'Jeez, just as I try to build something, stuff constantly pops up. Gotta stop being distracted.'

Re-examining the domain, Lan noticed that Remy was far from the only one who turned into a Magic Beast. In fact, several Monsters were undergoing Core Formation at the moment.

Most prominent among them in the Second Chamber was the good ol' deer herd, a part of them manatizing their bodies, Lightning Horn absorbing the most mana.

In fact, he was the one who finished the process first, finishing up forming his Heart Core. Surprisingly, even though he had no Mana Crystals near him, his Core did get an attribute, being slightly purple in color, arcs of electricity occasionally forming on the surface. It was quite obvious that it was of lightning element.

That confirmed one of Lan's theories about the fact that a Monster that has an affinity will probably gain the same attribute for the Heart Core.

The Lightning Horn then underwent physical changes. Thankfully he didn't increase in size, being big enough already. Instead, mana patterns engraved on top of his horns became more elaborate, having begun to shine with a weak light even without being used to shoot lightning.

Also, mana patterns became apparent on the Lightning Horns' body, covering it in mysterious patterns. Interestingly enough, as they covered the left, wounded side of his face, the point where the eye should have been began shining with a purple light.

Now the Lightning Horn seemingly had his eye back in a way, as for whether it was functional or not remained to be seen.

Lan felt quite sentimental about the Lightning Horn, as he was one of the first bigger creatures that became a domain dweller of Lan's. As such, Lan felt that he was deserving of a name as well. Small problem though, Lan was bad at naming. As such, Lan picked the easiest solution.

'Lightning... Horn... I got it! Your name is now Lorn!'

As yet another case of bad naming struck again, a sliver of Lan's mental mana was yet again transferred and embedded in Lorns' soul, Lan witnessing it this time.

'Huh? What's this?'

Being confused, Lan examined closely the connection with Lorn. Other than the usual increase of mental mana output because of the evolution, Lan felt something... Else.

Usually, the mental connection lets Lan suggest various things and images to the connected one. Also, he could somewhat read their thoughts and intentions, although it became somewhat vague with the more intelligent Monsters, such as The Huntress, 'reading' her was really hard.

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However, after he had named Lorn, he could feel yet another... Link between them. As if he could feel... The Core of Lorn's being, the central clump of mental mana, the 'soul'.

Lan didn't know however what exactly that meant, as other than feeling the link to it, that soul giving out a feeling of being anchored, nothing else changed.

After observing for a while longer, Lan gave the whole matter a mental shrug, as he could find out nothing more at the moment.

'Turning' to look at the rest of the herd, they have achieved various degrees of success in their manatization. All of the Steelhorns succeeded, forming their Cores, however, they didn't possess innate lightning affinity, and as such neither did their Heart Cores.

Instead, their Heart Cores shone in soft green light, patterns of the same color enveloping them. It would seem that Lorn was unique among them with his Lightning affinity.

Lan had never seen such mana, but he could easily speculate on what it was, as the feeling it gave out was all too familiar.

'Life Mana.'

It would seem that Steelhorns somehow got a Life Mana affinity, maybe because of the time spent among the forests, Lan didn't know for sure.

Lan then observed the few remaining Greater Deer, which were constantly dwindling after being subject to various attacks. However, although they underwent the manatization process as well, things were different here.

The biggest one among them succeeded in forming a Heart Core, it being a light blue color surprisingly. Somehow that one got a Water Mana affinity.

The others weren't that lucky in that regard, however.

The other Greater Deer did disintegrate their organs, though from that point on things were different. After said disintegration, during the Core Formation, things went wrong. The mana gathered around the heart, turning it into mana, and forming a crystal. However, that crystal was way smaller than a normal Heart Core.

It didn't shine in any light, but rather it was opaque. Those Greater Deer didn't obtain any mana patterns or mana affinity. It could be said that the crystal, which could not even be called a Heart Core, but rather a False Heart Core, only made sure to keep the Monster alive, not being a source of magic.

Those Greater Deer have failed in Core Formation, becoming stronger than a Monster, but weaker than a Magic Beast.

'I guess they could be called... Half-Magic Beasts.'

A unique case among them was a female who was pregnant. Although she did disintegrate her organs as well, the fetus remained intact. It was encased in a membrane of mana, and it was constantly being fed mana instead of nutrients. Even though its' mother remained a Half-Magic beast, what it would be born as remained to be seen for now.

The scenes of manatization and evolution appeared constantly throughout the whole domain, triggered by the Core Connection. Lan guessed that it would be a one-time occurrence, which would be good.

As for the reason why it was detrimental, well, because many of the monsters didn't possess an affinity yet, their manatization left the Domain with a lot of Half-Magic Beasts, and not that many Magic Beasts.

Surprisingly though, the pair of wolves all the way back in the Entrance Chamber seemed to be amidst the Core Formation process, signifying a possession of affinity.

The male wolf's Heart Core shone in a white and bright light, the mana it gave off was unfamiliar to Lan, being warm and bright.

Lan remembered though, that the said wolf liked to laze around in the light, sometimes even going outside to bask in the sunlight. This prompted Lan to name said affinity the Light Affinity.

Another curious detail was that his previously midnight-black fur rapidly whitened as if it was bleached. Soon, there stood a white wolf with glowing patterns on him. The light shimmered around him, sometimes making it seem as if the wolf wasn't there, and sometimes it seemed as if there were multiple of him.

After observing this, Lan decided to name him 'Tag', which in the German language meant 'Day'. He wasn't feeling creative.

The mate of Tag was undergoing Core Formation as well, though the resulting Core was the complete opposite of Tag's.

It was dark, seemingly absorbing light instead of radiating. Instead of being warm and bright, it felt cold and dark. Being the opposite of light, Lan named it Shadow Affinity.

Her already dark fur became even darker, to the point where it became hard to distinguish where the edges of her body were as if she was blending in with the darkness. Her mana patterns couldn't be seen either. However, what could be seen were her now-crimson pupils, as if two spots of light floating amidst the darkness. Pretty creepy-looking, to be honest.

Matching her mate, Lan named her 'Nacht' which meant Night.

Completing the Core Formation, the pair howled in celebration, sending out yet another pulse of mana. Though soon they were back to sleeping and cuddling together.

At this point, Lan wondered whether they would descend further down. However, they showed no indication of doing so, staying near the tunnel leading down, otherwise just guarding their puppies which were nearly fully grown compared to couple of days ago.

'I wonder if i should build a separate room for them, as they are the strongest beings in this Chamber... This ties up nicely with my idea of Floor Guardians. A Mana Beast may be a bit strong for the entrance, but they can always go down when i make further floors...'

As Lan was just about to build the 'boss room', he noticed something different about the mana.

'Is it just me, or the ambient mana here is higher?'

Checking it out once again, Lan confirmed his guess. With the mana cycling being sped up by the Core Connection, the concentration of ambient mana increased, and as such...

'That means I can make this room bigger now!'

Excited, Lan immediately got on with it. Previously the Entrance Chamber was approximately 30 meters in length. Pretty cramped compared to the rest of the underground domain.

So, with newfound amounts of mana, he expanded it (startling all dwellers in the process) until it was around 100x100 meters, same as the Second Chamber which he would soon expand as well.

Acting according to his words, he expanded the Second Chamber soon too.

In the end it became around 300x300.

As Lan 'sighed' in satisfaction, he noticed something odd.

'...Does some of the mana come back from above? How is that possible? Mana only comes from underground.'

Lan immediately began to investigate. In doing so, he stumbled upon an unexpected find.

'Roots?'

He found a roots spreading above the Entrance Chamber, mana moving upward was absorbed by them, and they themselves seemed to expel some Life and Neutral mana out of themselves.

As for the source of those roots, well...

Lan was met with an unexpected sight.

'Since when was there a giant tree on top of my Hill?!'