Lin Yan emerged from seclusion. Today, the Family delivered another batch of Relic Gu they had collected, and he needed to sort through them carefully.
Over the past six months, with the help of the two Families, he had gathered fifteen Red Steel Relic Gu and twenty-four Green Copper Relic Gu, spending around one hundred and eighty thousand primeval stones, all paid by Young Master Zhang.
To be honest, the amount was still a bit low, and future gains would likely become scarce. The reason the two Families had a stock of twelve White Silver Relic Gu was due to long-term accumulation over centuries. In contrast, Red Steel and Green Copper Relic Gu had high circulation. Most Rank 1 and Rank 2 Gu Masters would refine them immediately after obtaining them, leaving almost nothing behind.
With the Relic Gu he currently held, Lin Yan had already refined two Rank 5 Purple Crystal Relic Gu.
In theory, he could directly refine an Obstacle Breaking Gu and push himself to Rank 5, but he chose not to. It would be far more valuable to keep them for increasing his cultivation after reaching Rank 5.
Lin Yan had not wasted the past six months. With his A-grade, ninety-eight percent aptitude, he was already close to breaking through to Rank 5 and would likely succeed within a few months.
As for the Zhang Family's remaining debt, including the refinement materials he had requested, it had already reached around five hundred thousand primeval stones. He planned to request another three hundred thousand worth of refinement materials to upgrade his core Gu to Rank 4.
This required careful choice. It was impossible to upgrade all his Gu to Rank 4, as that would greatly increase the burden of feeding them.
For example, he decided to abandon Fire Claw Gu. Although it was linked to his killer move, Hand of Destruction, he already had a better replacement in Six-Armed Heavenly God Gu. Moreover, Fire Claw Gu lacked a follow-up refinement recipe.
The same applied to Flame Blade Gu. It had no supporting Gu to fully unleash its power, and it could be replaced by Rank 4 Golden Jade Sharp Fire Gu. This Gu combined the properties of Metal Path, could corrode the body and turn it into metal, and could form different sharp weapons, making it far stronger than Flame Blade Gu.
Accumulated Ash Gu lacked a Rank 4 Gu Recipe, but its potential was high, so Lin Yan decided to keep it for now.
In total, aside from the core of the Flame Demon True Body killer move, the Fire Heart Gu, he still needed to refine eight Gu: Exploding Fireball Gu, Flame Armor Gu, Treading Fire Gu, Fire Eyes and Golden Gaze Gu, Fire Source Gu, Sparks Gu, Burning Wind Gu, and Splash Gu.
Among these, Burning Wind Gu and Splash Gu would serve as the main materials to co-refine a Rank 4 Blazing Fury Gu, which carried the properties of both Flame Path and Rule Path.
He once again immersed himself in deducing Gu recipe in his dreams. Whenever he felt mental fatigue, he would stop and test newly obtained Gu or experiment with killer moves.
After a month, Lin Yan successfully refined Fire Heart Gu, the core of the Flame Demon True Body. At the same time, he had fully mastered all Gu Recipes of the Fire Pattern series.
Inside the quiet room, he held a crystal-clear crimson Gu shaped like a heart. Taking a steady breath, he poured in primeval essence, activated it, and pressed it firmly against his chest.
The next moment, Lin Yan felt his heart twitch violently, and a piercing pain surged through his body, almost cutting off his breath. Cold sweat covered him as the Fire Heart Gu continuously poured out intense vitality, forcefully transforming his body.
Buzz, buzz, buzz!
After an unknown amount of time, his face turned pale, as if he had just come out of a furnace. Yet within his chest, something like a small sun rose, blazing with light, shaping itself into a radiant heart that spread warmth through his entire body.
With the Fire Heart as the core, nine crimson-gold patterns appeared across his skin. His bones glowed faintly through his flesh, and several fire acupoints shone like scattered stars, making his whole body look clear and refined.
His blood flowed like molten rubies, carrying heat and power, as if his entire body had been forged from burning metal.
Fire Heart Gu was a one-time use Gu. With this Rank 4 core established, Lin Yan could maintain part of the Flame Demon True Body even in his normal state.
He could clearly feel the change. His body had become much stronger, his vitality surged like fire, and his recovery speed greatly increased. The enhancement to Flame Path Gu was obvious, and even a simple movement could stir up intense flames.
The effect was overwhelming. His combat power rose sharply, and he continued cultivating without pause. Time passed quickly. A year and a half had gone by since he killed Zhang Bai.