Gu Yi sensed something was amiss, but facing the vengeful corpse of Principal Hao, his entire focus was consumed by the thought of smashing him down, which inevitably caused him to overlook certain details until Bai Ru cried out, "Watch out!"

Glancing over, Gu Yi couldn't help but frown. He noticed that the strands of vengeful energy that had been continuously seeping in through the iron gate were not all being dispelled by the Eight Trigrams Protection Array. Quite a few lingered in the mid-air, and by this time, they had gathered into a large mass of mist, floating not far from them. It seemed to be deliberately avoiding the maximum range of the shield emitted by the array, as if someone were subtly controlling it from the shadows.

Bai Ru pulled out several talismans, preparing to leave the protective formation to aid Gu Yi, but as Gu Yi turned back, he told her, "Don't come out. We are being watched. If both of us leave, we might be wiped out in one fell swoop. Whatever is secretly observing us is waiting for us both to exit the formation together."

Bai Ru bit her lip, her expression turning quite grim. Gu Yi managed a relaxed smile and said, "Don't worry, I can handle it." As he spoke, he dodged the five fingers Principal Hao was wildly scratching toward him. The fierce wind generated by the sharp nails grazed past his cheek, giving the sensation that his hand had transformed into a beast's claw.

After missing the attack again, Principal Hao staggered back two steps, his teeth grinding with a loud clack-clack. Gu Yi wasn't sure what he was planning, so he thrust his Demon Subduing Staff directly toward his throat.

But just then, the mass of vengeful mist that had been stationary in the air suddenly moved. The swirling fog rapidly formed a vortex, emitting a low whoo-whoo sound as it rolled downward toward Gu Yi.

Not wanting to engage the mist head-on, Gu Yi had no choice but to withdraw his staff, tapping his toes on the ground and leaping backward. Unexpectedly, the mist, having missed its target, seemed unwilling to let Gu Yi go. It formed a visible whirlwind on the ground, sweeping toward Gu Yi as it spun. Its speed was considerable; even from a distance, Gu Yi could feel a faint, stinging pain on his face where the edge of the whirlwind scraped by.

Not only was the whirlwind itself closing in, but streaks of cyan energy shot out from within it. Just before reaching Gu Yi, these streaks suddenly transformed into fragmented limbs and torsos of various animals—heads, claws, tails—biting, clawing, or lashing out. Several even managed to score wounds on Gu Yi's face and hands.

Gu Yi batted away the various shapes of mist with his staff, feeling a slight surprise while also being grateful that he hadn't chosen to confront the large mass of vengeful mist outside the iron gate earlier.

While the whirlwind, constantly taking on different animal shapes, engaged Gu Yi, the vengeful corpse Principal Hao was not idle. He didn't charge toward Gu Yi along with the whirlwind; instead, he abruptly turned and headed toward Bai Ru, who remained within the Eight Trigrams Protection Array.

In the blink of an eye, Principal Hao reached the perimeter of the array, and even Gu Yi didn't have time to react. Forced to deal with the whirlwind formed by the vengeful mist, he couldn't return to Bai Ru's side quickly.

Standing at the center of the array, Bai Ru had no staff; she relied solely on the talismans to keep the formation active. However, her magical power was finite. The protective shield created by the array could only defend those inside; it couldn't generate offensive measures. Principal Hao, visibly brimming with potent vengeful energy all over his body, intended to use that energy to resist the shield's effect and then rely on his superhuman strength to shatter the barrier outright.

It had to be admitted that this was the crudest but currently the most effective method. Although Bai Ru had physical training, she had never truly engaged in martial arts. Dealing with formless spirits was not a major issue, but now she faced a vengeful corpse imbued with both malice and brute force, appearing in the guise of Principal Hao—though looking at the corpse now, one could hardly recognize anything of the original Principal Hao.

Should she leave the formation or remain inside? Bai Ru’s thoughts raced through several possibilities before she decided to wait and observe. Besides using talismans to enhance the Eight Trigrams Protection Array, she occasionally flung fire talismans toward the vengeful corpse. Unfortunately, these were either dodged by the corpse or nullified by the dense mist of vengeful energy swirling around its body.

The vengeful mist enveloping the corpse acted like a layer of armor, effectively protecting the core of the vengeful spirit—Principal Hao. Whether it was an illusion or genuine excess of internal energy, under the flashlight beam and the array's soft glow, Bai Ru thought Principal Hao's body seemed to have swelled by several sizes. His face was shrouded in a hazy gray as if covered by a layer of fog, yet his two eyes were clearly visible, wide open and unmoving, seeming ready to pop from their sockets at any moment. His eyeballs appeared gray, shriveled, and dull, clearly belonging to no living person, yet Bai Ru felt a venomous glare flickering within them.

Standing outside the shield, he raised both arms high, like a clumsy bear, putting all his strength into slamming against the protective barrier. Each strike caused the shield to flare with sparks of light, jarring Principal Hao back a few steps before he immediately rushed forward again to strike.

Bai Ru observed that although Principal Hao’s stance while attacking the shield resembled an upright bear, his movements were anything but sluggish. In fact, the intervals between his strikes were growing shorter; it looked like the shield formed by the Eight Trigrams Array wouldn't last much longer before being smashed apart.

This was a minor weakness stemming from insufficient magical reinforcement for the array. The shield was highly effective against spiritual entities, even capable of resisting the vengeful mist. Who would have thought that the opponent would utilize a walking corpse, augmented by an outer armor of vengeful energy, to counter the shield so effectively?

Comparatively, Gu Yi was successfully bogged down by the whirlwind formed from the vengeful mist. He tried several times to break through the barrier of swirling air in front of him but failed. He could only charge directly into the whirlwind, which seemed too risky.

Suddenly, Gu Yi shouted loudly, "Do rubber boots conduct electricity?"

Bai Ru was momentarily stunned, then seemed to grasp Gu Yi's intent, responding, "Do whatever you need to do. A little shock might even cure a cold."

Gu Yi chuckled, "I need a medium."

Bai Ru glanced at the central drainage ditch, let out a soft sigh, quickly found another talisman, and walked to the edge of the protective barrier. Trying to keep clear of facing Principal Hao directly, she flung the talisman into the drainage ditch outside the array while chanting, "Command of the Five Elements, Water Spirit Borrow Power, Rise!"

Instantly, the foul water in the ditch churned violently, surging skyward in waves, splashing directly onto the cement road on both sides of the sewer. This immediately resulted in large puddles forming on the ground. Bai Ru threw two more talismans, and soon, the stench-ridden standing water covered the area, even reaching the area under the vengeful mist whirlwind. As a result, the wind began shooting out sprayings of water like raindrops, and Gu Yi was quickly struck multiple times.

At this moment, Gu Yi naturally couldn't bother about being assaulted by the foul water. He immediately pressed the hand seal he had formed onto his Demon Subduing Staff. Using the inscribed runes on the staff as a medium, the enhanced Heavenly Thunder Talisman was unleashed.

At once, countless blue arcs of electricity erupted across the water surface centered around Gu Yi. Dazzling blue lightning snakes darted around, accompanied by the characteristic pili-pala crackle of electrical sparks from all directions.

The spectacle of dancing silver snakes enveloped the entire sewer. The electrical light not only illuminated the surroundings but was so intense that Bai Ru involuntarily squeezed her eyes shut, unable to look directly.

After a long while, the loud pipa sounds gradually faded until they disappeared, leaving only the occasional solitary arc skipping across the water surface, emitting a faint zizizi of electrical current.

Bai Ru opened her eyes only to quickly close them again. The afterimage of the intense light lingered on her retina for a moment before vanishing. When she reopened her eyes and looked around, she found the surroundings had returned to darkness, with only the faint yellow glow of the protective array remaining. In the distance, Gu Yi stood stock-still amidst the puddles, smoke curling from his hair, a pair of sunglasses clutched in his hand. His fair face was blackened by the electricity, making him look like he had just plunged headfirst into a coal bin.

"That was awesome," Gu Yi spat out a mouthful of saliva, sighing with satisfaction.

The vengeful mist whirlwind had vanished without a trace, and Gu Yi took a breath, regained his composure, picked up his staff, and strode toward Principal Hao. The lightning display hadn't affected the vengeful corpse of Principal Hao at all; he was still diligently battering the Eight Trigrams Protection Array, whose shield rippled like water, appearing as if it might shatter at any moment.

Gu Yi swung his Demon Subduing Staff. As he neared Principal Hao, he leaped into the air, aiming the staff directly at the back of the corpse's neck. Unexpectedly, even while smashing the shield, Principal Hao detected the threat from behind and instantly spun around, raising both arms to shield his head. Gu Yi’s strike hit his arm, but it didn't penetrate the flesh. Instead, Gu Yi felt a rebound force, causing his momentum in mid-air to stall. He had no choice but to land back on the ground.

Helplessly, the moment his feet touched the ground, Gu Yi instinctively raised his leg and kicked toward the space between Principal Hao’s legs. Truthfully, this move was merely to prevent Principal Hao from lunging at him in that moment, but the result was completely unexpected. His kick landed solidly below the abdomen, right between the corpse's legs.

Vengeful corpses, much like regular zombies, have bodies that are mostly hard as iron; hacking and smashing are generally ineffective. However, vengeful corpses have one key difference: if one can locate the specific body part where the mass of vengeful energy that caused the reanimation is hidden, the probability of dealing with it increases significantly, and that location is also one of the corpse's weaknesses.

The problem was that this mass of energy could be hidden in any part of the body, and the sensation Gu Yi felt from his kick was decidedly soft. This meant his kick had found the location of the vengeful energy that caused Principal Hao's transformation.

But the area he hit gave Gu Yi a chilling feeling, and he instinctively flinched, his mouth curling into a grimace.

Principal Hao, having taken that kick, reacted noticeably. His body swayed twice, and a mournful howl escaped his mouth, much like a normal person’s reaction to being struck there. His legs buckled, and he fell forward onto the ground.

Gu Yi was both shocked and delighted, allowing a rare, sinister grin to spread across his face. He swiftly flew forward and landed squarely on Principal Hao's back. He struggled to keep his balance amidst the corpse's violent thrashing from side to side, pinning it down so it couldn't rise.

However, his mounting position wasn't ideal—it was too high up, only managing to suppress Principal Hao's upper body struggles while being too far from the actual weak spot.

Gu Yi looked up in frustration and called out to Bai Ru, "Need a hand?"

Bai Ru asked uncertainly, "Where?"

Gu Yi tossed the Demon Subduing Staff upward, feeling somewhat annoyed. "Between the legs..."

Bai Ru leaped out of the protective array, caught the staff one-handed, and muttered a single word, tinged with exasperation: "Damn."