Upon hearing Su Yao's warning, everyone immediately stopped what they were doing and stared intently into the depths of the dark river. As the energy fluctuations intensified, the river water began to churn violently, as if some enormous monster was about to burst forth from the water.

"Whatever it is, we must deal with it carefully." Ling Yu gripped his ice sword, ready for battle.

Suddenly, a gigantic serpent leaped out of the underground river. Its body was thicker than a water bucket, covered in blue scales that shimmered eerily in the dim light. The serpent's eyes gleamed like two bright lamps, radiating a cold, chilling light, and its gaping maw was filled with sharp fangs.

"This water python doesn't seem simple; its scales appear to be able to defend against attacks," Su Yao said after scanning it with the system.

The python let out a deafening roar and lunged at Su Yao's father, who was closest to it. Su Yao's father hurriedly dodged, but the python was incredibly fast and was about to bite him. At this critical moment, Ling Yu rushed forward, his ice sword stabbing fiercely at the python's head. However, the ice sword struck the python's scales, only sending up a few sparks, and did not cause any real damage.

"Its scales are too hard; ordinary attacks are useless!" Ling Yu shouted.

Su Yao calmly considered the situation, recalling the methods for subduing creatures like serpents recorded in the system. "Attack its eyes and abdomen; those are its weak points!"

Ling Yu changed his attack strategy, using his ice-based ability to create a layer of icy mist around the water python, disrupting its vision. Then, seizing the opportunity, he transformed his ice sword into a beam of ice light and shot it towards the python's eyes. The python, in pain, frantically shook its head, its massive body creating towering waves in the dark river.

Su Yao used her spatial abilities to teleport to the lower abdomen of the water python. A sharp blade formed from spatial power appeared in her hand, and she forcefully stabbed it into the python's belly. The python's abdomen was relatively soft, and Su Yao's attack successfully pierced its skin, causing green blood to flow out and drip into the river water.

The serpent, feeling excruciating pain in its abdomen, struggled even more furiously. It lashed its massive tail at Su Yao, who quickly used spatial teleportation to dodge. At this moment, Su Yao's mother and the cloaked figure joined the battle. Su Yao's mother continuously shot crossbow bolts into the serpent's eyes to distract it. The cloaked figure, meanwhile, drew runes on the shore, attempting to trap the serpent with their power.

After a fierce battle, the group finally found the rhythm of the water python's attacks, and their teamwork became increasingly seamless. Ling Yu successfully struck the water python's other eye, rendering it completely blind. Taking advantage of the opportunity, Su Yao launched a fatal blow, her spatial blade piercing deep into the water python's heart. The water python let out a miserable cry, its massive body crashing to the ground, splashing up a huge spray of water.

Everyone was panting heavily, exhausted, but they knew the danger wasn't completely over. Su Yao's system detected a mysterious energy surging deep within the dark river, seemingly related to some kind of treasure or powerful technology.

"Should we continue exploring further?" Ling Yu asked.

After thinking for a moment, Su Yao said, "Now that we're here, we can't miss this opportunity that could change our destiny. But everyone needs to be even more careful."

So they continued deeper into the underground river. At its end, they discovered a huge cave. Strange lights shimmered within, and various ancient instruments and crystals exuding a mysterious aura were displayed.

Su Yao's system began frantically collecting information from these instruments and crystals. Analysis revealed that the instruments were climate control devices left behind by an ancient civilization, while the crystals were the energy cores driving these devices. If these devices could be repaired and utilized, they might be able to alleviate the extreme heat of the post-apocalyptic world to some extent.

"This is our chance! We must bring these things back to the safe house," Su Yao said excitedly.

However, just as they were preparing to move the devices and crystals, many mechanical golems suddenly appeared around the cave. These golems were tall, made entirely of metal, and their eyes glowed red. They slowly walked towards the group, clearly intending to prevent them from taking these precious items.

"We're in trouble again, but we can't back down!" Ling Yu said.

The group rallied their spirits, preparing for a new battle. They knew that these relics of an ancient civilization might be the key to their survival in the high-temperature apocalypse and to changing the world.