Level Up: Assassin.

Alastor exhaled deeply, a dense red mist escaping his nostrils and mouth as his eyes snapped open. He sat cross-legged on his bed, having just completed a session of blood refinement.

The world had changed drastically with the arrival of the Abyssal Gate. Along with the gate came the Abyssal Seed and monstrous creatures, ushering in an era of chaos. But amidst the destruction, a unique energy known as Fluxion also emerged.

Unlike the other forces that brought immediate, noticeable changes, Fluxion remained hidden from human perception. It wasn't until the emergence of ability users that humanity became aware of its existence. These individuals were the only ones capable of sensing and utilizing this potent energy.

Fluxion's primary use was to supercharge an ability user's heart. It sounds dangerous, and for ordinary humans, it would be. When an ability user absorbs Fluxion, their heart rate skyrockets, beating hundreds of times faster than a normal human heart could withstand. But for these individuals, a faster heartbeat is directly linked to increased power.

The process is surprisingly straightforward. As the heart races under the influence of Fluxion, it pumps and circulates blood at an accelerated rate. This rapid movement refines the blood, purifying and enhancing it. This refined blood, in turn, makes the ability user stronger, pushing them to higher levels of power.

There's no scientific explanation for why this works, but it does. And since there haven't been any widespread negative side effects, no one's complaining.

There have been a few isolated cases of complications, however. These have always been attributed to user error – either attempting to absorb more Fluxion than the body could handle, losing concentration during the delicate process, or experiencing external disruptions during the refinement.

"That was incredibly refreshing," Alastor murmured to himself.

"I wonder how much more I can handle. I can barely feel myself approaching any kind of limit."

It was common knowledge that every ability user had a limit to how much Fluxion they could absorb. But for Alastor, it felt different. Instead of hitting his own personal limit, it seemed the available Fluxion in his surroundings was depleted first. The sensation of being starved of Fluxion was completely foreign, but then again, so was his unprecedented 100% bloodline activation.

'Oh, right, the training!' A sudden thought jolted him.

"System, how long until my training starts?" he asked.

[30 seconds], the familiar, childish voice responded.

"What? That soon?" Alastor exclaimed, shocked.

What if he had continued the blood refinement process? Would the system have transported him mid-session? And what about the potential consequences? He had heard enough horror stories about the dangers of interrupting blood refinement, including fatal outcomes, to last a lifetime.

But he knew he couldn't really blame the system for the lack of warning. He had received the notification an hour ago. But his curiosity about blood refinement got the better of him. He had just wanted a quick taste, a few minutes at most. Lost in the sensation, he completely lost track of time.

There was no time to assign blame now. He had barely any time to react. Thankfully, he had prepared for this.

Unlike the training simulations, this training session involved a real-life location. The system had been very clear – he would receive no assistance. He needed to be completely self-sufficient. The only clue he had been given was that it involved survival. With that in mind, he had meticulously gathered everything he thought he might need.

With a blinding flash of light, Alastor felt an immense pull. He was being transported, ripped from his familiar surroundings and thrust into the unknown. The uncertainty of what awaited him was unsettling, to say the least.

Moments later, the pulling sensation stopped, signaling the end of Alastor's teleportation. He opened his eyes, expecting to see whatever training ground the system had chosen for him. Instead, he found himself speechless.

"What the…" Alastor cursed, his mouth hanging open in shock. This wasn't what he had pictured at all.

When the system mentioned survival training, Alastor imagined a dense forest, a scorching desert, or some other equally challenging environment on Earth. Never, not even in his wildest dreams, had he envisioned the sight before him.

Towering over him was a massive tree. Its expansive branches spread out like a giant umbrella, but it wasn't the tree's size that shocked him. It was the leaves. They glowed. Bathed in a multi-colored luminescence, the leaves cast a soft, ethereal light, creating a pool of illumination around Alastor that pushed back the encroaching darkness.

The entire scene was utterly alien.

"What the fuck is this, system? Where am I? This clearly isn't Earth, right?" Alastor finally managed, regaining his composure.

[Host is correct, this is not Earth. This is planet Vrym], the system's childish voice replied.

"Yeah, no shit. What I want to know is why the hell there's a glowing tree here?!"

[The tree's glow is a result of a unique mutation, an adaptation to the planet's specific conditions.]

"What conditions?"

[Planet Vrym is shrouded in near-perpetual darkness. In fact, 90% of the day is dark. This has forced the planet's flora and fauna to adapt, leading to various mutations, such as the glowing tree.]

"Oh, I see," Alastor muttered, scanning his surroundings once more.

'But why does this darkness feel… different?' he wondered. Before he could ponder the thought further, his ears twitched, picking up a sound behind him.

'Fuck,' he cursed as his instincts roared to life, compelling him to move.

A shadow flashed past with incredible speed, narrowly missing him. Thanks to his own exceptional reflexes and agility, Alastor felt only a whisper of displaced air, not the searing pain of teeth sinking into flesh. The sound of snapping jaws, aimed at his abdomen, echoed behind him.

'What the hell was that?' Alastor thought, adrenaline surging through him as he watched the shadowy outline of his attacker disappear back into the darkness beyond the reach of the glowing tree and the equally luminescent grass that carpeted the ground.

From what little he could discern, the creature resembled a canine, but massive – a wolf, perhaps, but significantly larger.

Lost in the chaos of the moment, his guard momentarily down, Alastor's danger sense flared again. More rustling, closer this time.

'Fuck, there's more than one,' he cursed silently.

He had been so focused on the first attack that he hadn't noticed the second creature stalking him.

Now, with barely any time to react, Alastor's mind raced, calculating his next move. The first attack had made it clear: these creatures were incredibly fast. Even with his own impressive speed and reflexes, escaping unscathed from this range was highly improbable. He had to make a choice, a difficult one, and quickly. He decided to take a calculated risk – a minor injury in exchange for a chance to strike back.

The entire thought process took a fraction of a second. By the time he had made his decision, he could feel the air displace as the second creature lunged.

In a blur of motion, Alastor reacted, his honed instincts taking over. He spun, his hand darting to the dagger sheathed at his waist, ready to meet the attack head-on.