Their plan for all of the rooms was paramount on the green mangrove trees. They are trees that grow strictly in water, with an intricate root system living in the water, with the rest of the trees growing out of the water.

The environment that is created from the growth of the mangroves is a leafy environment above the water and a root system that will make it more challenging to traverse and provide hiding areas for ambushes.

Taking the clipping of the mangrove tree, the child grew the tree in the first room, allowing the roots to root into the soil and the water, and a thin trunk growing out of the water with its branches spreading out, making a canopy across the top of the ceiling. Then, cutting off multiple trimmings from the tree, the child recreated this process in all of the rooms. But in the fifth room, they did something different.

Since there were only fifty centimetres of air, there would be no room for the mangrove trees to grow out of the water, and that was not what they wanted for this room anyways. They wanted to create a maze-like area, challenging to navigate underwater, with the roots. So when they grew the plant, they made the mangroves' trunk, stems, and leaves grow in a densely-packed flat circle at the top of the water. The majority of the growth of the mangroves within the fifth room is composed of the root system.

They did the same thing with all the other mangroves in the room, leaving a thick foliage of roots and only a few places within the room to breathe for those who need air to breathe.

With the mangrove forests fully grown in the rooms, the child continued with populating the rooms with plants before they worked on populating the hallways with plants.

On the mangrove canopy, they grew string moss, red trumpet vines, and mist orchids, and around the exposed roots, they placed black dripping mushrooms and bird ferns. In addition, they grew tangled fan grass, ice blast seaweed, sharp seaweed, bubble weed, shrub seaweed, and swollen short seaweed within the water. Though they placed six species of seaweed throughout the rooms, they made sure that they were only placed sporadically.

They wanted to avoid packing the rooms with seaweeds, and since the water was turning darker and darker, and its makeup was changing as well due to the swamp mana string, they wanted to keep up the swamp theme for the rooms.

They packed the hallways with these six aquatic plant species, as well as grasping gel seaweed and blade seaweed.

Floating throughout the rooms and hallways, they placed pieces of floating moss.

With the plants in place, the child added the fauna portion to this environment.

The air and land creatures added yellow finches, white moths, clouded white butterflies, brown singing frogs, tormissus water beetles, elachista moths, and crystal dwarf spiders, gray water snakes, brown mosquitoes and cold water bees.

Of the aquatic creatures, they placed knobbed sea snails, fisher alligators, longnose spookfish, shortnose chimaeras, sawtooth eels, red-tentacled box jellyfish, swift pinfish, large bank bass, cloak spadefish, silver anchovies, weaving crabs, red sea star, orange mottled sea squirt, and wandering anemones.

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As all of the animals spread within the rooms and hallways, the child focused on placing the monsters onto the floor. Unlike floors one to four, the child decided that they would add all of their monsters, but their positions within the floor would be restricted to certain areas.

They allowed the ice krill to roam through the hallways, and they made tunnels small enough that the krill could move through them to access the other hallways that were only connected by going through the rooms so that the krill can reach all of the hallways, not just one section of them.

Within the rooms, they placed the alluring vines within the branches of the mangroves, and in the fifth room, they put them in the circular bunch of the mangrove's trunk, branches and leaves, making the vine monster hang within the water. It was a long shot putting the monster into the water, but the vines seemed to be okay with it.

The last to be placed was the ravenous snails, which controlled the rooms' aquatic portions.

And with that, a screen popped up.

Congratulations! You have completed your fifth floor!

Present Creature Species: 25

Present Plant Species: 14

Present Monster Species: 3

Each floor must have a floor boss for your sub-dimension to grow.

After they finished reading it, the child followed their instincts, and they started choosing a monster or swarm to make into their floor boss.

Within the first floor, the child chose an ice krill swarm that has had the most damage and kills against the adventurers. Taking their mana string and piercing every single one of the krill in the swarm, the child pumped their golden flecks within their strings into the swarm.

The ice krill grew to 15 centimetres long, became a lot more attuned to each other as a swarm, making the swarm have more of a hive mind, and their ice attacks became a lot more dangerous. Normally their ice attack would only cause light burns on skin, and depending on how long the ice was on a person's skin, the damage would be more severe, and the expansion rate was slow. But their first krill swarm floor boss's ice travelled faster, creating much more severe burns with a simple touch. So they decided to call it the "hive krill swarm."

Congratulations! You have made the ice krill swarm your first-floor boss and have named it the "Hive Krill Swarm."

The second-floor boss they chose a speedy ravenous snail. When they inserted their mana strings and added mana to the monster, the snail stayed the same size, but it became more compact, more made for speed. It gained another two fins to help with speed and maneuverability, and the teeth and hooks on its tentacles changed to be better attack weapons for hit-and-run attacks. The child named the monster floor boss the "clip snail."

Congratulations! You have made the ravenous snail your second-floor boss and have named it the "Clip Snail."

The third-floor boss they chose is a small swarm of ice krill that have developed this peculiar interest in jumping out of the water. Inserting their mana string, they focused it on the krill's ability to jump out of the water. The krill became longer and had a more powerful tail, allowing it to jump further out of the water. Their ability to use their ice has also changed, they used their ice ability to create a fine mist of ice that allowed them to glide through the air further, but the ice mist also came with the cost of rapidly freezing whatever it comes into contact with. So they decided to call this ice krill swarm floor boss the "jumping ice swarm."

Congratulations! You have made the ice krill swarm your third-floor boss and have named it the "Jumping Ice Swarm."

The fourth-floor boss they created was from an alluring vine at the end of the floor. While this is a stationary monster, when they added their mana strings, the monster proliferated, with ten more vines coming from its base and spreading out among the canopy. The vine also had its original vine produce many more flowers, which increased the allure of its scent, allowing prey to be lured into reach where the other ten vines could attack and kill it. The child decided to call it the "entice vine."

Congratulations! You have made the alluring vine your fourth-floor boss and have named it the "Entice Vine."

The last of the floor bosses that they chose was a ravenous snail that seemed to hunt prey in areas where their movement was reduced. After they inserted the mana string and changed the snail into a boss monster, the snail became even better at this. The snail grew to 30 centimetres long, and they gained the ability to change the colour of their skin to any colour to lure their prey to easily attacked areas. They called the fifth-floor boss the "Trapping Snail."

Congratulations! You have made the ravenous snail your fifth-floor boss and have named it the "Trapping Snail."

Two screens popped up as soon as the child chose and named all of their floor bosses and received screens confirming their choice.

Expansion of your sub-dimension from completing your fifth floor will now commence. Due to finishing the first five floors of your dungeon, your sub-dimension will gain an additional ten-metre expansion in width and height.

The maximum number of monster species within your dungeon has now increased by three until the completion of your tenth floor. This does not include monster species obtained from outside your dungeon.

As the child read through the screens, the child felt their sub-dimension increase in size.