The mark on Merlin's chest deepened in color, resembling a black mole. It radiated a faint, cool aura as dark elements continuously gathered around him. Within his mindscape, the **Dark Fog** and **Shadow Domain** spell models absorbed energy at an accelerated rate, a clear result of mastering the **Dark Heart.**
The **Dark Heart** naturally enhanced the affinity for dark elements, significantly boosting the power of dark-element spells—especially since Merlin had cultivated the third and most advanced form.
"Let's test this—**Dark Fog**!"
With a thought, Merlin released **Dark Fog.** Instantly, a thick mist filled the entire quiet chamber and even began to seep outward. Despite the room's size, the fog's reach had expanded drastically.
Before mastering the **Dark Heart**, Merlin's **Dark Fog** could barely cover a radius of 50 to 100 meters. Now, the spell's range and potency had nearly doubled. He could feel the mark on his chest heating up as an unusual force augmented his spell, much like a powerful casting tool.
Even with conservative estimates, the fog's strength had increased by almost 100%.
"This power… it's astonishing. **Dark Fog** alone is now comparable to a first-level spell. If I use the enhanced version, the results could be terrifying."
Eager to explore the possibilities, Merlin turned his focus to **Shadow Domain**—a more advanced spell that warped light, plunging entire regions into darkness with disorienting and hallucinatory effects.
In its base form, **Shadow Domain** could ensnare even peak second-level spellcasters in its illusions. The enhanced version could affect third-level spellcasters, potentially incapacitating them. Now, Merlin was keen to see how much more powerful this spell would become with the **Dark Heart.**
Clearing the lingering fog with a wave of his hand, Merlin channeled his magic into **Shadow Domain.** As the light distorted, an eerie darkness enveloped the chamber, creating an oppressive and illusory atmosphere.
"Enhanced **Shadow Domain,**" Merlin muttered as he unleashed the spell in its full form.
Once again, the mark on his chest flared with heat, amplifying the spell's strength. Even the enhanced version of **Shadow Domain** received an undeniable boost from the **Dark Heart.**
The results were extraordinary. Merlin could sense that even strong third-level spellcasters—or ordinary fourth-level spellcasters—would struggle against the illusions created by his spell.
"This is incredible," Merlin whispered. "With the enhancements from the third form of the **Dark Heart,** even high-tier opponents would falter. Ordinary fourth-level spellcasters wouldn't stand a chance."
Yet, Merlin acknowledged that not all fourth-level spellcasters were equal. Powerful ones with exceptional mental defenses might resist the spell's effects. Nonetheless, the **Dark Heart** had provided Merlin with an undeniable edge, pushing his capabilities closer to those of higher-tier mages.
"How long have I been cultivating?" Merlin asked, consulting the Matrix.
"Nine hours," it responded.
Merlin reflected for a moment. "To fully master the third form of the **Dark Heart** in just nine hours… that's exceptionally fast. It must be because of my strong mental fortitude. No illusion could shake me."
Having completed his cultivation, Merlin stood up and left the chamber.
---
### Outside the Chamber
As Merlin emerged, Leo and the other mages—Hobbes, Gecello, and Balin—immediately turned their attention toward him. Their intense gazes scrutinized him, their spiritual energies probing his newfound strength.
"Merlin, have you mastered the **Dark Heart**?" Leo asked, his usual composure giving way to a hint of anxiety.
The other mages exchanged glances. Though they knew of Leo's reputation for being eccentric and aloof, they found it strange that he seemed so invested in Merlin's progress. Even if Merlin was a six-element prodigy, Leo's sacrifices and efforts seemed excessive for a mere mentor-student relationship.
Merlin, sensing Leo's concern, smiled. "Yes, Leo. Everything went smoothly. I've successfully mastered the **Dark Heart.**"
The other mages showed no surprise. When Merlin had emerged from the Abyssal Maze after seven days, it had been almost certain that he could cultivate the third form of the **Dark Heart.** Still, hearing him confirm it solidified their admiration.
"Good." A rare smile appeared on Leo's face. Reaching into his dimensional ring, he retrieved an ornate, bound manuscript. "Hobbes, here is the first half of the **Dark Eye** cultivation method I promised."
Leo handed the manuscript to Hobbes, who, along with Gecello and Balin, eagerly gathered to examine it. Their eyes gleamed with an almost childlike fascination.
Though the document was only a few pages long, the three mages spent over half an hour poring over it. Even Merlin felt curious about the contents of this legendary cultivation method.
Leo, however, remained calm and patient, seemingly unsurprised by their reactions.
Eventually, Hobbes raised his head, his expression one of awe and reverence. He exchanged glances with his companions, all of whom shared the same look of disbelief.
"Incredible," Hobbes murmured. "Leo, this method… even our founder, the great Damani Archmage, couldn't create something like this. And yet you've done it. I must say, I am deeply impressed."
"Indeed," Gecello chimed in. "Even with only half the method, we can see its brilliance. Leo, your innovation is truly unparalleled."
Leo nodded, his face showing no hint of pride. He had anticipated such a reaction.
"When will we receive the second half?" Hobbes asked eagerly, his composure breaking slightly under the weight of his excitement.
"Once Merlin has chosen his spells and we leave the Abyssal Fortress, you'll receive the rest," Leo replied evenly.
Hobbes nodded, though it was clear he could hardly contain his anticipation. Turning to Merlin, he said, "Merlin, follow us to the library. You can select one spell for each tier, from second to sixth. Take your time."
Merlin nodded and followed the group as they made their way through the fortress's labyrinthine passages. The atmosphere grew denser with dark elemental energy as they approached their destination. Finally, they arrived at two massive stone doors adorned with ancient carvings and mysterious runes.
"This," Hobbes said, gesturing grandly, "is the library."