Just as Onean predicted, the Skycourt Kingdom's mercenaries were unwilling to accept defeat, and that very same night, they were up to no good again. They were felling trees to build a path to replicate the mountain path that had been destroyed, and by the time Erwin and the others rose up into the sky on the airship, they discovered that the Skycourt Kingdom's mercenaries had already sneakily completed around a third of their makeshift path.

"These people just don't know when to give up, do they?" Erwin murmured to himself as he looked at all of the moving people and flickering torches at the foot of the mountain.

"Hold on, what are those things that they're holding in their hands?" Chase suddenly asked.

Even though they were able to see a lot further from their vantage point on the airship, it was still impossible to see exactly what the Skycourt Kingdom mercenaries were doing due to how dark it was at night. All of a sudden, the torches were quickly snuffed out one after another, and in what seemed like no more than the blink of an eye, the entire scene had been plunged into darkness.

"What just happened? Why did everything suddenly turn dark?" Larwood made his way over to the railing, then leaned forward as he peered into the distance through narrowed eyes.

Right at this moment, Christine silently handed a monocular over to Erwin.

"You had something like this the entire time? Why didn't you give it to me earlier? My eyes were straining so hard this morning that I felt like I was getting a headache," Erwin complained with an amused smile.

"I only found it just now after going through the entire airship. I thought those Skycourt Kingdom mercenaries lost it, but I managed to find it in the corner of one of the rooms," Christine replied in a low voice.

Erwin put the monocular to his own eye and looked out at the foot of the mountain in the distance, upon which a grim look appeared on his face. "I still can't see anything. It's like they've suddenly disappeared into thin air!"

"Let me take a look." Onean took the monocular from Erwin, but she was unable to see anything through it, either, and she quickly fell into deep thought, trying to think of an explanation for this bizarre situation.

"Don't tell me all of these Skycourt Kingdom mercenaries are ghosts," Kaiba said with furrowed brows.

"Hold on, could it be that they're using nightwalker?" Onean asked as a hint of realization dawned on her.

"What's that?" Erwin asked with a puzzled expression, a look that was mirrored on the faces of Larwood and the others as well. It was clear that Erwin and his three friends were all just as uneducated as one another.

"Nightwalker is a magic potion that can be brewed from powdered deer antler wasps. Deer antler wasps make their hives in the darkest bushes in the Terarody Mountain Ranges, and when gathered in great numbers, they can absorb large amounts of light from the surrounding environment. If there are enough of them present in one place, they could even transform day into night," Onean explained.

"So you're saying they used this nightwalker to absorb all of the light around them?" Larwood asked.

Onean nodded in response.

"But that doesn't make sense, either. If all of the light has been sucked away, then wouldn't they be blind as well? How are they supposed to walk along this narrow log path blind? All of them will fall to their deaths before they can even reach the city!" Erwin said with a bewildered expression.

Onean shook her head in response. "You don't know how this magic potion works. Not only is it able to absorb all light in an area, any living being who comes into contact with it will attain the same night vision that deer antler wasps possess. When using nightwalker, one will be able to see clearly even on the darkest of nights."

"So you're saying those Skycourt Kingdom mercenaries are already sneaking toward the city as we speak?" Erwin asked as his eyes widened with alarm.

Onean raised a finger to her own lips to make a silencing gesture, and Sherry and Lanyon immediately took this as an order as they began instructing everyone on the airship to be quiet.

Soon, the only sounds that could be heard on the airship came from the blast furnace and the grinding gears of the vehicle.

For people like Onean and Georgina, the former of which was a magician who was very sensitive to the movement of matter particles in the environment, while the latter of which was an assassin who was very perceptive when it came to sounds, they could already sense that there was some irregular activity taking place on the mountain.

Soon, Erwin and the others were also beginning to notice that something wasn't quite right.

"Christine, drive the airship forward a little bit," Erwin instructed.

Christine did as she was told, and thus, the airship flew on a little further from the point where the battle during the day had taken place.

Immediately thereafter, Erwin unleashed an illumination blast spell directly toward the area under the airship. The white light glided through the darkness of the night for a stretch before fading. Erwin was observing the spell intently, and he remarked, "The spell faded naturally, so it wasn't absorbed by the nightwalker potion. It looks like the Skycourt Kingdom's mercenaries haven't made it to this point yet."

"Don't you guys find what these Skycourt Kingdom mercenaries are doing to be rather strange? Did they not suffer enough after being bombarded by that meteor shower spell from Her Highness during the day? They can clearly see that we're prepared for a sneak attack in the night, so why are they still insisting on going through with the attack?" Chase asked with a perplexed expression. "Are they not afraid of being bombarded by Her Highness again?"

"I was just wondering that myself. Surely they've already spotted our airship hovering above the city on lookout duty, so why are they still being so reckless?" Larwood mused with furrowed brows.

"Let's think about that another time. For now, we should focus on preventing these Skycourt Kingdom mercenaries from completing the log path. Lanyon, gather all of our magicians and bombard the mountain with spells. We may not be able to see them, but they have to be down there somewhere," Erwin instructed.

Lanyon accepted the order and quickly assembled all of the magicians on the airship. Upon receiving an instruction from Lanyon, all of the magicians began to fire spells onto the pitch-black mountain down below. The spells exploded to produce a display of spectacular lights, but all of the dazzling lights faded in the blink of an eye, and it was impossible to tell whether the spells had struck the Skycourt Kingdom's mercenaries or had merely fallen upon the mountain.

Francis was looking on while standing atop the city wall of Xeto, and upon hearing the commotion ringing out in the distance, he knew that the Skycourt Kingdom mercenaries at the foot of the mountain were indeed up to no good. At the same time, he was feeling very fortunate that the princess had convinced him against holding a celebratory banquet. Otherwise, the city would've been far more susceptible to a sneak attack from these cunning Skycourt Kingdom mercenaries.

"Listen carefully... Do you hear that?" Onean asked as she turned toward Erwin.

"I do. It sounds like there are drums being struck, but the sound is a bit too dull for it to be drumming," Erwin replied. "What is this sound? I feel like I've heard it somewhere before."

"Isn't this the sound of spells striking shields?" Kaiba exclaimed with an enlightened expression. He was thinking back to the sparring matches that had taken place between him and Erwin during the offense and defense classes. This was the exact same sound produced by Erwin's instant-release spells striking his shield.

An enlightened look also appeared on Erwin's face upon hearing this, and he turned to Larwood with wide eyes as he exclaimed, "They're already directly below us!"

Larwood reacted very quickly, issuing a loud order to all of the Four Winds mercenaries on the airship's decks. "All martial artists, fire your arrows!"

A volley of arrows was let loose, and as opposed to the dull thuds produced by the spells striking the shields, what resulted instead was a string of loud clangs.

By listening to where the sound was coming from, Larwood was able to roughly determine the location of the enemy mercenaries, and he pointed a finger at a certain flatter part of the mountain as he said, "That's most likely where they are right now. I was wondering why they dared to venture up the mountain, they think that they can deal with Her Highness's magic using their shields."

"Just how naive are they? They think the nightwalker potion and a bunch of shields would be enough for them to bypass us?" Erwin was quite amused by the thought.

"I was also thinking the same thing. Surely they don't think that they'll be able to ward off Her Highness's spells with their shields alone," Chase chuckled with a hint of mockery in his eyes.

Erwin and Onean exchanged a glance, following which both of them sprang up into the air.

With a wave of Onean's staff, bolts of lightning were drawn down from the heavens. The peculiar bolts of blue lightning in the night sky struck the top of her staff, while magic power instantly surged out of her hand, guiding the lightning and releasing it from the bottom of her staff as a series of rapidly expanding arcs of electricity. 

The countless tiny arcs of lightning hurtled directly toward the spot on the mountain where Larwood had just pointed toward, and the sudden emergence of so many quivering arcs of blue lightning under the pitch-black night sky presented quite a harrowing sight to behold.

Due to how close Erwin was situated to Onean, he could sense that these thin arcs of lightning were imbued with extremely potent armor-piercing properties. It was no wonder that Onean had guided the lightning spell onto her own staff before releasing it. As it turned out, she was altering the properties of the spell through her own magic power.

This was not a technique that any magician could pull off. Generally speaking, in order to impart a powerful negative status condition upon a spell, one would either have to use a large amount of magic power to infuse the negative status conditions into the spell during the process of elemental matter conversion, or rely on pieces of equipment such as staves and rings. Erwin was a practitioner of the latter option.

To do what Onean had just done, which was to convert elemental matter into magic energy, then impart a negative status condition upon it in a short time with her magic power, one would require incredible reserves of magic power and a wealth of experience in handling spells. If the magic energy couldn't be properly controlled, then there was a chance that it would surge directly into her body.

However, the advantage of utilizing this method was that it would be far faster than normal to unleash spells imbued with powerful negative status conditions like this one.

...

Sure enough, the thin arcs of blue lightning were able to strike the enemy forces, and as their blue radiance danced through the inky-black night, a string of agonized howls immediately rang out across the entire valley. As it turned out, these thin arcs of lightning had already pierced through the shields that the Skycourt Kingdom mercenaries had prepared and directly struck their bodies. Due to the effect of the nightwalker potion, there was still no light coming from the mountain, so it was impossible to see how many casualties the Skycourt Kingdom mercenaries had suffered. However, judging from the commotion ringing out from the mountain, it was clear that they were suffering severe losses.