Investing in My Harem in the Apocalypse Makes Me Stronger

The enormous reserve inside his body converged toward a single point.

Mana compressed continuously until the energy became so dense that Cain could feel an uncomfortable pressure building inside his chest.

Then something began taking shape.

A small sphere.

At first, its structure remained unstable.

Mana flowed across the surface irregularly, occasionally spilling outward before being pulled back in.

Cain did not interfere, since the advancement itself seemed to know what needed to happen.

More energy gathered and the sphere became increasingly complete.

Then something within his body responded.

Dark gray energy that remained throughout Cain’s body after the battle suddenly moved toward the forming Core.

The moment the two touched, Cain felt the entire structure tremble.

Dark gray currents spread through the sphere until every trace of Mana inside it gradually became infused with the same destructive energy Cain had borrowed from the Primordial Chaos Dragon since the apocalypse began.

The change felt completely natural as there was no rejection between his Mana and Ruin element.

If anything, the two seemed as though they had always belonged together.

’A Ruin Mana Core...’

Cain focused on the forming structure as it began rotating.

Every rotation drew more Mana inward before compressing and refining it.

At the same time, energy started flowing outward again.

The moment that refined Mana entered Cain’s body, another transformation began.

His muscles tightened violently.

The bones beneath them became denser, while the exhaustion that had nearly overwhelmed him after the fight rapidly weakened.

Cain immediately understood what was happening.

This was the same advancement Nathan and the others had gone through.

The moment their Mana Cores formed, their Stats doubled.

Now it was his turn.

Power continuously surged throughout Cain’s body as the difference between Unranked and 1st Echelon was finally erased.

At a distance, Ron noticed the change within Cain’s body immediately.

His expression became serious.

He immediately grabbed his spear and moved closer as he knew that Cain was in the process of advancing to 1st Echelon.

His eyes swept across the surrounding streets.

The battle had brought them far enough away from the main group that the area was unusually quiet.

Several abandoned vehicles remained scattered along the road. Broken glass covered part of the sidewalk, while cracks from their fight spread across the pavement.

Ron could not sense anything approaching.

Still, he remained alert since Cain was completely focused on his advancement.

If another evolved zombie appeared now, Ron would have to handle it until Cain finished.

His gaze eventually passed across the Zombie King’s corpse.

Something orange was glowing beside it.

Ron blinked.

”Oh?”

He approached cautiously and saw an Orange Scroll lay near the headless body.

Beside it rested an Orange Orb.

Ron looked between the loot and Cain.

The Mana gathering around his friend had already become violent enough to make loose stones tremble near his body.

Ron immediately picked up both items.

He had no intention of using them as these were Cain’s loot.

Besides, Cain had already promised him a Yellow Scroll after the battle was finished.

Ron had never seriously worried about Cain refusing to give it to him.

Cain might be shameless enough to steal his food and somehow explain why it was his fault for leaving it unattended, but he knew that Cain wasn’t that shameless to scam him after all that had just happened now.

Because when Cain gave his word about something important, he kept it.

Ron was far more concerned about leaving the Orange Orb anywhere near Cain right now.

If the disturbance from the advancement somehow caused it to roll across the ground and crack open, Ron already knew exactly who would be blamed afterward.

It was definitely him.

He carefully placed the Scroll and Orb inside his clothes before stepping back, then his attention returned to Cain.

The transformation was still continuing.

Inside Cain’s body, the newly formed Ruin Mana Core finally stabilized.

Under normal circumstances, that should have been the end of the advancement.

Nathan’s Core had remained at the Newly Formed Stage after reaching the 1st Echelon.

However, Cain’s Core did not as the enormous amount of Mana gathered inside him continued pouring toward the Core.

Its rotation became faster.

The faint instability around the surface disappeared almost immediately as the structure became completely steady.

Stabilized stage.

Cain barely had time to recognize the change before the Core compressed again.

The energy inside became much denser.

Its previously fluid structure grew increasingly solid until the Core felt almost physical despite existing entirely from Mana.

Solidified stage.

Cain’s eyebrows twitched beneath his closed eyes.

’It’s still going?’

He had not absorbed a single Core yet.

The resources inside his Inventory remained completely untouched, yet the transformation showed no sign of ending.

Ruin energy circulated throughout the Core repeatedly.

Whenever Cain sensed even the slightest irregularity within its structure, the dark gray energy passed through that section and destroyed whatever instability remained.

The Core became smaller as it continued compressing.

However, the amount of power contained inside did not decrease.

It was quite the opposite as the Mana became far denser than before.

Cain suddenly remembered Nathan explaining the Core Stages.

Newly Formed Stage.

Stabilized Stage.

Solidified Stage.

Then Tempered Stage.

The name immediately made sense.

His entire Core was being tempered repeatedly by Ruin.

Cain did not know whether this happened because of his enormous Mana reserve, the quality of his Ruin element or the connection to the Primordial Chaos Dragon.

Perhaps all of them contributed.

He could investigate later.

For now, Cain allowed the process to continue.

Ron watched from outside as the disturbance gradually changed.

The wild Mana that had been rushing toward Cain moments earlier suddenly became strangely controlled.

Dark gray currents occasionally appeared around his body before being pulled back beneath his skin.

The pressure continued rising, then everything stopped.

The road became quiet again.

Cain remained seated for several seconds.

Finally, a notification appeared.

[Ding! Your Mana Core has reached the Tempered Stage.]

Cain slowly opened his eyes.

A faint dark gray glow briefly flickered within them, then it disappeared.

Cain immediately focused on the Core inside his chest.

The difference was enormous.

His Mana no longer flowed loosely throughout his body.

The Ruin Mana Core continuously circulated and refined it before sending the energy outward again, making every current considerably denser than it had been while he remained Unranked.

Cain clenched one hand, a wide smile appeared on his face.

”Tempered Stage already...”

He had expected to spend all of the Cores he possessed to reach this stage.

However, he had reached it immediately after advancing without touching a single one.

That meant every Core he had prepared could now be saved for pushing even farther later.

There were still two stages after the Tempered Stage, which was the Flawless Stage and eventually Perfected Stage.

Cain looked toward Ron and noticed him standing near the Zombie King’s corpse.

His eyes immediately moved toward the slight orange glow hidden beneath Ron’s clothes.

Before Cain could ask what the bastard had taken, another notification rang inside his mind.

This time, the sensation was different as a massive translucent screen appeared in front of Cain.

The same screen appeared before Ron, then across Earth and eventually, the announcement continued far beyond the world they knew.

[Universal Announcement]

[The first player in the entire Universe...]

[The name ”Heavenly Dragon” shall be recorded in the history of this Universe.]

[Heavenly Dragon has received ???.]