I will expand now on some general advice in regard to the sewer system of a dungeon town. Sanitation is of vital importance to the ongoing health and safety of any large settlement. No one wants to live in a town with rivers of filth flowing down the streets.

Experts in Earth mana can make quick work of the task, creating reinforced tunnels below the city to divert waste. If no Earth mages (or mages with other relevant Ideals) are currently available, the task can be completed with manual labor. Considering the extreme difficulty of constructing sewers manually, it is almost always cheaper to pay for an Earth mage to be transported to your location. Ideally, an Earth mage should have been among the initial group to secure the newly located dungeon entrance.

One unique risk which sewers in dungeon towns must take into consideration is, of course, the dungeon itself. While the higher floors of a dungeon are usually relatively stable, there are cases in which higher floors will move, expand, or shift considerably. If a dungeon cave should come to intersect a section of sewer, the results can be disastrous. Imagine the panic when monsters start crawling out of the toilets.

As such, it is advised to only use shallowly buried pipes too small for any dungeon monsters to fit through within the expected activity radius of the dungeon, along with a reasonable buffer zone. If cost is not an issue, considering removing sewage entirely from the area around the dungeon and using magical alternatives, such as water stones and nothingness pits.

Outside of the area directly surrounding the dungeon, large and wide subterranean sewers are recommended. Spacious tunnels will make future repairs and management much simpler. As an added bonus, large sewers can double as back-up shelters during a wave or other natural (or unnatural) disaster. Making the tunnels larger than necessary also helps avoid the risk of overflow during heavy rains.

-Excerpt from Making a Labyrinth Town: From Outpost to Metropolis

The demon Valefarraximalicafarius, known by his alias Vale Farwind, sat in a comfortable leather chair, looking down over the ongoing battle from the top floor of the Geltheas city bank. In his hand, he slowly swished a crystal glass filled with the finest Pancal wine, a specialty of the region. A look of dissatisfaction marred his statuesque face.

This was not proving to be the disaster he had hoped for. "So they found the mana sink and removed it... what a shame." The dodecahedral artifact had been difficult and expensive to craft, and had been likewise arduous to place without being detected. Unfortunately, it had been even more effective than planned. The city leadership had noticed the spike in monster production, and that troublesome Leader had likely sniffed out the artifact during the resultant sweep by using his Unique skill.

Valefar took a slow sip of the wine. Even in this secluded place, it was necessary for him to retain his human shape. It would be troublesome of someone below were to look through the window while he showed his true form. There was also the matter of the soldier standing behind him.

"What do we do now, general? Should we call off the attack?" An ant nearly as large as a horse stood upright on its hindmost legs in stiff attention behind the demon's chair. The soldier wore a grey military jacket and peaked cap tailored to the creature's unique anatomy. Several well-polished medals adorned the jacket's left breast. Despite the chittering and clacking of mandibles as it talked, the voice had a distinctly feminine tone.

In truth, Valefar wasn't really concerned about actually winning this battle. A loss here would still cause the human suffering the demon craved. It would only be the nation he had infiltrated suffering instead of the nation of Pancal. Of course, he could not admit as such openly. "No, Lieutenant. We will proceed as planned. It's unfortunate, but we've already invested too much in this operation. And besides," Valefar glanced out of the window towards the east. "If it has already been found, then it's only a matter of time until the artifact is traced back to the Phagia Republic. They probably already handed it over to the Great Enchanter to examine."

"Understood, general. Shall I signal the confirmation?" The ant's antenna twitched slightly.

Valefar finished the remainder of his glass of wine. Delicious. "Yes, send the message. We'll let them tire themselves out for a while first. We'll strike at noon."

"Understood, general. Sending confirmation now." The ant settled into a fugue state as her antenna swayed wildly. Valefar settled into his seat to enjoy the show.

Mud was very pleased by the efficient manner in which the humans dealt with the dungeon wave event. Despite the inherent danger of fighting a large number of monsters, there had as yet been no fatalities. A few delvers and soldiers along the front lines had received injuries, but they were quickly rotated out and healed by nearby specialists.

In one case, a city guardsman had acted carelessly and even had his head taken clean off by the sharp mandibles of a Glutton Worm. The support group had acted with incredible speed, quickly retrieving the man's head and repairing the wound before even a second had passed. The guard was forced to leave the battlefield due to mental shock, but seemed to have no lingering physical damage.

Next to Mud sat a male human mage in meditation, steadily releasing free mana for Mud to use. The pink-haired mage said that his Ideal of Love was not suitable for combat, and so he was helping in this way instead. While crafting the free mana into the Ideal of Home, Mud sent a message to Jabrax.

"Jabrax, can healing magic recover any damage?"

Jabrax relaxed on an invisible chair, leaning it back dangerously. "Yes and no. As long as an attack isn't fatal, a lifeform can be restored to their vision of self pretty easily. There are some medical problems that a magical solution hasn't been found for yet though, like aging. An injury that's so old that a person considers it part of their identity also can not be healed."

"Isn't a human's head being removed fatal?"

"Only if they die." Jabrax continued after a short pause. "Once a person's soul believes they've taken enough damage that their vessel isn't alive anymore, the soul will leave and the body can no longer be restored. But if you act quickly enough, the soul won't have time to realize it should be dead and leave the body, no matter how bad the damage is."

Cob chimed in, leaning forward enthusiastically. "I heard a story one time of a man being flattened under a falling chunk of masonry. His body was completely crushed to paste." Novus balked at the description as Cob continued. "Luckily, there was a powerful priest nearby. I think around tier six. He cast a healing spell in a flash and the pile of blood and guts actually came back together. He was good as new. Went on live a normal life."

"That story sounds made up, but it's certainly possible." Jabrax nodded slightly.

"If I truly believed that I could not die, then would I be able to recover from any damage?" Mud was already plotting how to brainwash itself.

"No." Jabrax immediately dashed those plans. "It's all about how your soul sees its role within the false world through the twisted- um, I mean, it has nothing to do with conscious thought. You would need to shape your soul into a shape that has the inherent quality of immortality."

"Are you saying there are classes that can make you immortal?" Cob rubbed his chin. "You wouldn't happen to know how to get a class like that, would you?"

"It's purely hypothetical. Sorry, but you'll just have to grow old and die like the rest." Jabrax's relaxed pose and grin made it clear she was not sorry. "Anyway, it would probably be easier to do with species rather than class. For example, demons are immortal. Even if destroyed, they just reform in the abyss."

"I wish I was a demon..." Cob stared off into space while Jabrax nodded approvingly.

The conversation was cut short by the pink-haired mage snapping back to wakefulness. "Apologies, but I've run dry. I'll need to go and recover for a time. My replacement should be here shortly." After standing he made a slight bow towards the party, then departed through the back of the pillbox.

Shortly after a new mage entered. A woman with a shaved head. She refused to reveal what her Ideal was and simply sat down to release free mana. As such, Mud continued casting Kill Pest for several hours. During this time, he gained several more levels, eventually reaching level eleven in Master Butler. Unfortunately, the increasing levels had reduced the experience income even further. Now, even Corpse Worms gave zero experience. At a combined level of twenty-one, Mud was now technically a tier three.

At noon, something changed. Multiple simultaneous explosions erupted from far behind Mud.

Vale Farwind sipped his wine as the rooftops and wooden platforms below were utterly obliterated by the maelstrom of magic artillery shells detonating. Normally, they were completely safe to store out in the open or handle roughly. Only by being inserted into the barrel of the cannons could their enchantments be activated, allowing them to detonate after being launched.

Phagian ingenuity had bypassed such safeguards. By simulating the interior of the cannons over a wide area using a single-use enchantment, all of the projectiles had been primed. A second tool had triggered them to explode. If Geltheas were fighting a human nation, then precautions against such methods would have certainly been taken. But against nearly mindless insects? It would have been a pointless waste of resources. The magic required for this act of sabotage was far too complex for even a particularly clever Worm of the Tower.

But Geltheas were not merely fighting a wave anymore. As the chaotic energies faded, all that remained of the artillery installations was melted slag and piles of rubble. Below, the soldiers were in chaos. Like cockroaches escaping from light, the humans scattered in all directions. The carefully established order of the battlefield was in one stroke destroyed.

With the removal of the vital supporting artillery and the chaos of the back lines, the equilibrium of the front lines was broken. While the insects were far from intelligent, the higher tier ones had a certain animalistic cunning. They recognized the moment of weakness and grasped it.

The churning mass of worms surged forward with renewed vigor, Giant Caterpillars literally throwing themselves onto the soldier's weapons. Within moments, the soldiers were overwhelmed, the line collapsing. While the most powerful fighters were able to hold their own against the onslaught, such as Leader Ghul and Prince Cain, the majority were pushed back, and for the first time that day, there were deaths on the front lines.

To his credit, Leader Ghul was able to restore a semblance of order. Ordering the back lines to give everything they had without regard for preserving resourcing, he was able to halt the advance, forming a new line in front of the pillboxes.

The battle would be much more difficult for them now, but with his leadership and proper coordination, they would still persevere. Geltheas was a town with rather cautious leadership, all things considered. Unlike some other dungeon towns, they had multiple contingencies and safety nets in place for dealing with waves. Under normal circumstances, it was extremely unlikely for even a single defending soldier to die during a wave. Such was the lengths of their precaution.

Even if the line were to be completely broken, they could simply retreat and allow the town to be overrun, then take their time slowly reclaiming the city. It was far from ideal, but the civilian fallback locations were designed to be safe even when attacked by a Worm of the Tower, which was the most powerful creature the dungeon could produce. It would be economically disastrous, but not the end of the city. The people could always rebuild.

Of course, that's all assuming they were only fighting the dungeon.

"Wonderful. At least this part of the plan is a success." Behind him, the ant chittered in agreement. "Send the signal to attack directly. Don't give them any more time to recover."

"Understood, General." The ant's antenna waved wildly.