Prologue — The Heart of the Summoner

KA-BOOM—!

The ceiling of the Tower came crashing down with a deafening roar. Red alert windows flickered one after another across the air.

From within the haze of drifting dust, Sung Jeyeon kicked aside the rubble of broken stone and forced herself upright.

Damn it all.

Her breath came in ragged gasps. Her ears rang with a shrill whine, and her vision — tangled in blood and dust — warped into a bloody smear.

Beyond it, she heard Ki Taewon's voice.

"Sung Jeyeon! Are you okay?!"

Ki Taewon, asking after her with such worry in his voice, was himself soaked head to toe in blood, his right arm hanging broken at his side. Behind him, a shadow like some monstrous black beast writhed and coiled. The final boss — the Lord of the Tower. Every colossal step that being took shook the entire Tower to its foundations.

Jeyeon stared at the numbers hanging in the air.

The end was right there in front of her — close enough to see, too far to touch.

Ten years. It had taken humanity exactly ten years of climbing the Tower to reach this final floor. If they failed here, there would be no second chance.

Ki Taewon spoke, his voice cracking.

"If this keeps up, we both die."

Their mana had long since run dry. No more attacks. No more summons. Nothing left.

He forced the words out, each one heavier than the last.

"Sung Jeyeon, I can't hold on any longer. You should at least—"

"Ki Taewon."

But Jeyeon cut him off, flat and absolute.

"What good would that do, when the whole world's about to disappear?"

A heavy silence settled between them as they looked at each other.

It wasn't as if Ki Taewon didn't know that already. He was probably just saying it because he needed to — because a lie like that was the only thing that kept him standing.

I can't let it end like this.

Jeyeon clenched her teeth and reached deep for her strength. But all her outstretched hand found was the raw sting of nails scraping down an empty wall.

Is this really it, then?

This long journey — all of it, paid for with so many lives — ending here?

...No.

There was exactly one thing left to try. One thing a mage like Ki Taewon could never do — but a summoner like Sung Jeyeon could.

The one thing in this world that only she could do.

"Ki Taewon. Take care of our kids."

"Don't you dare say that! I'm coming with—"

"There's no time."

Jeyeon's eyes flared blue.

"Pass the Book of Summoning on to the guild. It has to keep working. It has to."

She pressed the palm-sized book into his hand, leaving him no room to refuse.

"The rest — I'm leaving it all to you."

But Ki Taewon never answered. He only gritted his teeth and fixed her with a look full of grief and blame.

Jeyeon smiled lightly.

"Hey, Ki Taewon. Isn't this exciting? You're finally going to be the strongest in the world."

"...No. I don't—"

The instant he tried to shout something back, a massive magic circle bloomed to life beneath Jeyeon's feet.

"Summon."

Columns of blue light surged upward, tearing the darkness apart.

"□□□□, □□□□, □□□□ — and □□□□."

With each great name that rang out, the whole Tower shuddered. Light twisted and bent, and the Four Great Entities took shape within it.

But the ritual was not yet finished.

Jeyeon drew a short, sharp breath. Then she drove the blade in her hand deep into her own chest.

Blood geysered upward.

Clutching her still-beating heart in her hand, she began to chant.

"SUNG JEYEON!"

Just before Ki Taewon's outstretched hand could reach her, a blinding explosion of light swallowed everything.

Jeyeon's body rose into the air. Light coursed through every vein, and cracks like shattered glass spread across her skin.

Ki Taewon screamed.

"No — no, Jeyeon, please—!"

Toward her old friend, weeping in anguish, Jeyeon smiled.

"At least you — become the heart of the new era."

Thud—

Her heart beat one last time.

Jeyeon's body was torn apart, piece by wretched piece, within the light. And at the very center of that radiance, the Four Great Entities — fused into one — opened their eyes.

The Lord of the Tower let out a monstrous shriek.

The fused entity extended a hand, and the colossal beast scattered into ash and light. And then, the world fell silent.