There was once a man who was summoned to another world of fantasy and magic. After a while of surviving, gaining skills and even moving up in the adventurers guild, he died. Many years later he was reborn...

As a dungeon core.

This is his story. (now I can tag this as a reincarnation, summoned to another world, dungeon core story!)

BTW he lost a bunch of his memories.

Over many decades, a forest far to the north of the great city of Argrovad had been growing in its mana density. So much so, that monsters were spawning and breeding there at an alarming pace. Because of this, the area has been devoid of travelers for a long time. Only the bravest of adventurers dare to get anywhere close.

When the mana density reached a peak, the forest shuddered for miles.

A large amount of the mana started to get sucked towards the center of the forest. As the mana was getting pulled to the center, it was so thick, that it looked like a giant circle in the shape of a blue wave crashing in on itself.

When the mana was gathered at a single point, it coalesced into an ocean blue, fist sized crystal.

All the monsters in the area started to panic Some ran in all directions, some started viciously fighting amongst themselves.

One curious boar headed to the center of the condensing mana to see what happened.

Congratulation, you have been reborn as a dungeon core!

"OH MY! WHAT THE HELL IS HAPPENING???" (this is the dude, not the boar)

You have been reborn as a dungeon core, in order to proceed, you need to claim an area of the ground. This will unlock further options. Would you like to claim this area for your dungeon? Y/N?

The curious boar began to sniff at the unprotected dungeon core.

"I was reborn as a dungeon core?"

Yes, you have been reborn as a dungeon core, in order to proceed, you need to claim an area of the ground. This will unlock further options. Would you like to claim this area for your dungeon? Y/N?

Before he could answer, the nearby boar got too curious, and gobbled up the dungeon core, it was too hard or its teeth to penetrate, so the boar swallowed it whole.

Giving into his fate, the un-named, summoned dead guy made a choice.

"Yes I would like to claim this area as my dungeon"

Congratulation the area within 10 meters... ERROR.....ERROR... WHAT THE HELL HAPPENED... ERROR... WE JUST STARTED!... ERROR...

(that was the system panicking)

Would you like the system to automatically fix the errors? Y/N?

"Ummm, yes?"

Scanning, and fixing errors, please wait

After waiting for three whole minutes, there was a response.

A new substance (not dirt or rock) has been claimed as the dungeon. A non stationary area has been chosen for the dungeon. Dungeon mechanics have been altered. All further upgrades have been altered.

The boar dropped dead on the spot like a sack of bricks.

Congratulation you have scored your first kill. + a bunch of xp + a bunch more for the level difference You have gained a level Check your status for information and options

The un-named, summoned dead guy, had a slight intuition of how things worked.

"Status"

level 2 inanimate flesh and blood dungeon

Floors 1

minions 0

health 30/30

mana 15/15

stamina 20/20

unused dungeon upgrade points 2

upgrades

options

more stats and options will be unlocked with further upgrades, and levels

"options"

spawn monster

create - plants, minerals...

set trap

move materials

"upgrades"

Upgrades available:

mobility (one time purchase)

skills + (the plus means there is a list that can be viewed)

dungeon expand

add new spawn monster

create second floor (this option is grayed out, can't be selected now)

Expand stat sheet (more things can be viewed on the stat screen, also adds upgrade options)

The dungeon core had taken place right next to the boars heart.

He could feel every inch of the boar.

"I can't just lie here like a sitting duck."

"I don't have the underground protection like other dungeons, so first I gotta deal with protection."

"I spend one point on mobility"

Mobility upgrade selected.

First he started looking around, his limbs were jerking slightly.

"I thought I would be able to tell the boar where to go, I did not think I would be the freakin boar!"

He stood up quickly, and jumped and ran around a bit, to get used to the new body.

"Looks like I'm a half a meter tall male boar."

"I wonder what dungeon expand does"

Dungeon expand selected

"WAIT I DIDDN'T SELECT THAT!"

His boar body dropped to the floor, he began to squeal in pain.

(oh by the way up until now all his words were in his head)

"SQUEEEEAL"

"SQUEEEEEEEEEEEEEEEEEEEEEEEEAL"

After an excruciating minute and a half, the pain stopped, and he stood back up.

Checking out his body, he had grown a lot, now he was a meter tall. (with all four feet on the ground)

"whoa that was a serious upgrade."

Due to your increased size, your ambient mana intake has increased

"oh that’s good."

"How do I get more mana?"

Your core automatically draws in mana from the surrounding area. More mana rich areas will increase the speed of mana intake.

"What happens to the extra mana when I'm full? can I store it away?"

When your mana is full the max mana in your dungeon core will increase. When you reach a plateau this can also increase your level

"I see it's at 15 now, how long will it take to increase?"

That is not your dungeon cores mana, that is the mana of the boar.

"What is my dungeon cores mana?"

It is currently at 30

"why cant I see it in my stat screen?"

Your stat screen is not upgraded enough yet.

"But I can just ask you anyways so whatevs yo"

"What can I do with my dungeon core mana?"

Dungeon core mana may be spent on various things, from setting traps, growing plant life, spawning creatures, and shifting materials. At advanced levels, you can set rules, create contracts...

He was feeling hungry and began to eat some grass.

A new plant has been acquired. You may now grow Grass

"Cool"

"uhh, grow grass!"

"Whoa, I feel like I have to take a huge dump"

"Wheres that grass I just made?"

It is in your large intestine

"whoa gross!"

"well I guess its not that gross"

"I mean I have had worse things in there"

"Well not in this boar body, but you know what I mean"

"OK well lets try to poop out some grass!"

He squatted a bit, but try as he might, nothing was coming out.

"Hey whats going on? why cant I poop?"

The grass is growing out of the wall of your large intestine, you will not be able to poop it out in the conventional way

"oh"

"well lets try moving it with my dungeon core mana"

"I select dungeon core mana and move the grass to the outside of my body"

"Why didn't that work?"

In order to move items you must use your will power. You do not need to say everything you select.

"OK, OK"

"focuuuus"

With his mind, he easily plucked the small patch of grass off of the wall of his large intestine, and worked his way through the winding maze until it came out of his backside, he then replanted it on the top of his back.

"Whoa that was easier than I thought it would be"

"whats that smell?"

There is some boar manure still attached to the patch of grass on your back

"Oh gross!"

He focused again, and was able to remove the grass, he tried planting it on the ground but could not, so he just left it on the floor.

"If eating grass lets me make grass, I could eat other stuff too!"

He started to eat random things that wee lying around.

new materials and species have been acquired.

You may now grow Sun Lillies.

You may now create Dirt.

You may now create Rocks.

You may now create Generic Tree Bark

You may now create deer poop.

"Lets see what I got here, Sun Lillies.... Rocks, I could be a rock mage or something... DEER POOP? WHAT THE HELL!"

*spitting

*spitting

*licking a tree to take away the deer poop residue

"Gotta be more careful next time."

Just then, he heard something moving in the bushes some distance away.

He wearily looked to see what it was.

"oh hey its a deer!"

"Hi deer, I'm a boar!"

The deer looked at him suspiciously, then it hissed and pulled back its lips to show long sharp bloody fangs.

"Hisssss"

"Oh what the crap is that!"

The un-named, summoned dead guy now living as a dungeon core that possessed a boar turned around and started running as fast as it (he?) could.

Unknowingly in the direction of the nearest human settlement. (even though it's really far away, but he is really scared and kept on finding scary monsters to run away from until he got kinda close to the human settlement, after stopping for some breaks, and a long run on sentence)