Hearing Bai Ru's words, Gu Yi knew she was thinking along the same lines as him. The simple reason why they arrived at the same conclusion almost simultaneously was the element of time.

In Wu Zhongyou's experience, the duration from when he watched those vehicles depart and then descended into the sewer, to the moment he turned a corner and spotted Principal Hao's grandson behind the wire mesh, was definitely much shorter than the time Gu Yi and Bai Ru had spent behind this very mesh since entering. The fact that they hadn't encountered the main target here, apart from the cyan, humanoid mist rolling and pursuing them from behind, confirmed this.

"What do we do?" Bai Ru asked Gu Yi.

Gu Yi didn't hesitate. "Run back."

It sounded simple, but it was far from easy. The mass of cyan Death Qi coalesced into a humanoid fog behind them was nearly two meters tall, its width occupying half of the sewer passage. This colossal entity was not only impervious to blades and bullets but also seemed capable of attacking them as if it were solid.

Bai Ru shook her head, dismissing the suggestion: "For now, we can't go back..."

She couldn't elaborate while running, only managed to say that much. In truth, Gu Yi understood; the prospect of simply running straight back was slim.

"Then... what?" Gu Yi couldn't immediately devise a countermeasure.

In some aspects, Bai Ru was far more observant than Gu Yi. During their hasty retreat, she had taken note of the sewer walls on either side. In this current section, there was an opening branching off from their left wall at intervals, but each was sealed by an iron grating. Only the central drainage ditch passed beneath the grating, emptying into the main drainage ditch where they now stood.

Bai Ru pondered for a moment and conceived an idea. Though unsure of its feasibility, it was certainly better than having no plan at all. She asked Gu Yi, "Is there any way to use the water in this central ditch to create a water curtain?"

"Uh..." Gu Yi hesitated. "That's sewage water..."

"Nonsense, I know that. Do you think I enjoy it?" Bai Ru responded helplessly.

Gu Yi's thunder talismans continued to deploy without pause. He said, "But you must understand, that thing behind us looks like mist, but Death Qi isn't ordinary vapor formed by tiny water droplets."

Bai Ru nodded. "I know. What I'm thinking is, use this foul water to freeze the creature's lower parts."

Gu Yi froze for a moment, then nodded in sudden realization. "That might actually work."

Before finishing his words, he was already in action, hurling two thunder talismans simultaneously behind him at the cyan figure, reaching to pull out another charm.

Originally, Gu Yi's Five Elements spell could be cast purely through hand seals, but to enhance the effect, he decided to use a talisman for added certainty.

"Five Elements Borrowed Magic, Surging Waves Overwhelm the Heavens, Bind..."

In the drainage ditch, waves churned the water surface, instantly surging into towering spray. A water curtain, thick and inky black like foul water, immediately materialized behind them, crashing down upon the cyan figure.

After the first talisman, Gu Yi did not stop; he continued to empower the water magic of his Five Elements spell with more talismans. Instantly, layers of water walls formed from the sewage appeared before the cyan figure.

As Gu Yi had predicted, the water walls couldn't truly impede the cyan figure's advance. The walls rose and crashed, yet passed right through its body, splashing back onto the ground.

Attacks of this magnitude obviously couldn't harm the cyan entity in the slightest. It paid no mind, and its speed did not slacken.

Bai Ru naturally understood this too. So, as the next few water walls formed, she had already turned to face the cyan figure, swinging her Demon-Subduing Rod through the air while chanting: "Water God Borrowed Magic, Dripping Water Turns to Ice, Seal!"

Immediately, the arc of the rod trailed a faint, crescent-shaped shadow of light that shot into the water walls. As the walls tumbled toward the cyan figure, countless water droplets coalesced into hailstones of varying sizes, pelting down into the mist.

The cyan figure's forward momentum clearly paused for a beat.

A surge of joy ran through Bai Ru as her strike hit home. She quickly continued, retreating backward while swinging the rod, transforming Gu Yi's conjured water walls into endless hail.

The cyan figure's advance slowed progressively, until it finally stopped, merely waving its arms.

But that wasn't the end. Although the creature had ceased its pursuit, simultaneously, the "crackling" sound of stones falling onto the ground once again echoed in the sewer. They watched as countless scattered, barely recognizable animal remains in the surrounding drainage ditches slowly began to move toward the cloud of mist, as if pulled by invisible threads.

It seemed the creature truly relied on these animal skeletons to advance, and now it was clearly pulling them over to form its "feet."

Gu Yi and Bai Ru did not slow their forward sprint. Seizing this opportunity, they finally gained distance from the entity behind them.

However, Bai Ru had no intention of facing the creature head-on—not yet, at least. Their only goal now was escape. She pulled Gu Yi, pointing to a sealed branch sewer opening ahead. "Quick, in there, we go!"

Upon reaching the branch opening, Gu Yi realized the iron grating was different from the wire mesh they had entered through earlier. Clearly, the wire mesh was likely added later by those people, whereas this grating seemed to be original infrastructure for the sewer.

Staring at the iron bars nearly as thick as two fingers, Gu Yi nearly wanted to smash his forehead against them in frustration.

"No choice, hurry..." Bai Ru also saw the problem, but she wasn't overly worried; this shouldn't be too difficult for Gu Yi.

As expected, Gu Yi's earlier display had been somewhat exaggerated. He pulled out iron pincers and said to Bai Ru, "I'll use a True Yang Fire Talisman to soften this metal, and you can snip it. That'll be faster."

With that, he magically produced several talismans and affixed them to the iron bars, activating them with his spiritual power to burn continuously. Bai Ru, working in perfect synchronization, saw when the metal was softened enough and signaled him to extinguish the flame, then snipped through the bars with the pincers.

Soon, an opening large enough for them to crawl through appeared before them. They carefully crouched and slipped into the branch passage. Gu Yi turned back, setting up several Heavenly Thunder Talismans, ready to momentarily impede the cyan figure should it pursue them there.

They both understood that regardless of what the entity was called, tracking prey wasn't done by sight, but by sensing life force or aura. This sensing mechanism wasn't nullified simply by holding one's breath. If time permitted, they could temporarily conceal their auras, but they still needed distance to possibly shake it off.

Although this branch sewer also contained animal remains, it was evident this section didn't truly belong to the main barrier. Bai Ru checked the side walls; there was no extra cement added later.

Gu Yi asked as he ran forward, "What's the plan now? How do we get back?"

Bai Ru recalled the rough map of the sewer layout, mused for a moment, and replied, "There should be an exit to turn back, but we'll have to try. And once we leave here and return to the barrier, I don't know if that thing will still chase us."

Gu Yi asked no more questions, searching alongside Bai Ru for any other side passages in this section of the sewer.

This area was noticeably safer than before. Only the sound of their footsteps echoed in the vast, empty sewer. After running for an indeterminate time, they did see several side passages, but all were on the right side. According to Bai Ru's memory, those paths would only lead them further astray, not back.

Then, they finally saw a turn-off to the left, just like the entrance they had used before, sealed by an iron grating.

"This is it," Bai Ru said.

They repeated their method, breaking through the grating and scrambling inside.

After running for another ten minutes, Gu Yi suddenly put out a hand to stop Bai Ru. Just as she halted her steps, the sound of their running feet vanishing simultaneously, a faint scraping noise against the concrete floor drifted from ahead. In the silence of the sewer, it sounded jarringly loud.

In this section of the sewer they had just entered, there was definitely a third person ahead. Without exchanging words, they simultaneously adjusted their flashlight beams, angling them toward the front, where the light disappeared into the distant darkness.

Gradually, the footsteps sounded closer and closer to them...