As Su Yao and Ling Yu stepped into the radiant purification core, a powerful energy rushed towards them, seemingly threatening to engulf them. This energy was pure and vast, yet it contained wisps of lingering, impure dark energy.

"We must be careful; this dark force is still resisting," Su Yao warned. She activated the system, attempting to analyze the energy structure within the purification core and locate the key nodes for purification. After a quick scan, the system presented them with a complex energy network diagram, showing three main energy convergence points within the core, each corresponding to energy of different attributes.

"It seems we need to purify these three points simultaneously," Ling Yu said, looking at the energy network diagram. They headed in three different directions, ready to begin their operation.

Su Yao arrived at the energy convergence point representing spatial attributes. The space here was distorted, with dark forces lurking within its folds. She took a deep breath and used her spatial abilities to penetrate deeper. She discovered that these dark forces were like cunning vipers, constantly changing positions to evade her attacks. Su Yao focused her mind, using the system to precisely lock onto the traces of the dark forces, and then activated spatial compression, attempting to squeeze and destroy them.

However, the dark forces also began to retaliate, releasing spatial turbulence that assaulted Su Yao's mental defenses. Su Yao felt a sharp pain, but she gritted her teeth and persevered, constantly adjusting the frequency of her spatial abilities to increase the compression power.

Meanwhile, Ling Yu encountered a tremendous challenge at the ice-attribute energy convergence point. The temperature here was extremely low, even for him, an ice-type ability user. Dark power fused with ice elements, forming enormous ice spikes that shot towards Ling Yu. Ling Yu used his ice-type ability to create an ice shield to defend himself. However, the power of the ice spikes was too great, and the ice shield quickly cracked.

Ling Yu did not back down. He unleashed his ice-based abilities to their fullest extent, creating an ice domain around him. Within this domain, he was the master. He controlled the ice elements, dissolving the ice spikes one by one, and counterattacked against the source of the dark power. He used ice blades to cut through the dark power, attempting to separate it from the ice elements.

At the third energy convergence point, representing the realm of life, the situation is also dire. Strange energy vines grow here; these vines, which should have been full of life, have become extremely aggressive after being corrupted by dark forces. They lash out like tentacles, rapidly absorbing the energy of anything they touch.

Su Yao and Ling Yu worked together, sharing information through the system to adjust the pace of the purification. When Su Yao forcefully compressed the dark power at the spatial attribute convergence point, Ling Yu used the energy fluctuations of the Ice Domain to interfere with the vines at the life attribute convergence point, causing their movements to slow down briefly.

Then, Ling Yu seized the opportunity, temporarily abandoning his attack on the ice attribute convergence point and transferring his ice-type power to the life attribute convergence point, freezing the vines. Su Yao then used spatial teleportation to arrive at the life attribute convergence point and used spatial power to sever the connection between the vines and the dark power.

Through their combined efforts, the dark power at the three energy convergence points was gradually weakened. But just when they thought they were about to succeed, the dark power suddenly merged together, forming a gigantic dark shadow.

The demonic shadow let out a terrifying roar and pounced towards them. Its attack was highly corrosive, contaminating the energy of the purification core wherever it went. Su Yao and Ling Yu quickly moved closer, back to back, preparing to face the final challenge.

Su Yao activated her spatial abilities, creating multiple spatial traps in an attempt to imprison the demonic shadow. Ling Yu, on the other hand, continuously unleashed ice-based attacks to weaken the demonic shadow's power. The demonic shadow struggled amidst the traps and attacks; although its power was formidable, Su Yao and Ling Yu's teamwork was far more seamless.

During the fierce battle, Su Yao discovered that the core of the demonic shadow was located in its head, where the most concentrated dark power resided. She shared this information with Ling Yu, and the two decided to concentrate their efforts on attacking the demonic shadow's head.

They gathered all their supernatural abilities and energy, launching a final, fatal blow towards the demon's head. In a dazzling light, the demon let out a piercing scream before gradually dissipating. As the demon vanished, the dark power within the purification core was completely eradicated, and the "Heart of the Frost Source" began to emit a warm and gentle light, the world's vitality slowly beginning to revive.