Noah studied the roots entangled on the floating Kesier runes for months before feeling confident enough to modify them.
The Divine Deduction technique had never stopped illuminating the insides of his mental sphere in that period. That slowed down his training with Sword Saint a bit, but Noah had never held back when he found a way to improve his power.
The Demonic Form and the Black Mark had similar effects. Noah could already imagine the corrosive smoke carrying poisonous properties on top of its corrosive ability.
Still, he needed to modify the Demonic Form spell's very core if he wanted that to happen. Noah had to fuse the original idea behind the Black Mark spell into the roots, which was an invasive procedure.
Noah didn't focus only on the roots' structure when he studied his spell. He paid particular attention to the laws in their fabric and how they interacted with the Kesier runes.
The more he learnt about that diagram, the more he realized how complex it was. Yet, he understood that certain tricks were behind the creation of spells that didn't have limitations to their power.
The Warp spell, the Shadow Copy spell, the Body-inscription spell, and the Demonic Form all had external factors connected to their diagrams. The last two had quite obvious requirements, while the others only needed stronger mental spheres.
Having more external factors allowed the diagrams to be less complicated. They could have fewer lines since part of their effects depended on things unrelated to their core.
However, the Demonic Form ignored that theory. Its roots acted as if they were a parasite drawing power from the Kesier rune, even if they didn't hurt them in the slightest.
That would typically make any modification more difficult, but it made it easier for Noah. If he could treat the spell as a living being, he could make use of his expertise.
Noah felt as if he wanted to improve the species of the Demonic Form when planning its modifications. The roots weren't an actual lifeform, but that wouldn't matter as long as they behaved like one.
At first, Noah began experimenting with the small bits of roots that tried to cover the Seventh Kesier rune's almost-invisible shape.
Noah was nowhere near the seventh rank, so only the rune's faint shape had begun to form in his mind. The roots wanted to cover that too, but they could only hang from the Sixth rune after failing.
Imbuing wills in the matter was something that Noah had done since his time in the Royal Academy. The Elemental Forging method proved itself exceptionally useful in that situation.
Noah had to break down the Black Mark's spell to its core, translate it into a will, and forge it into the roots. His centuries of training in that inscription method made him confident in succeeding without hurting the spell.
A few failures happened, but Noah only lost part of the superfluous roots in the process. That didn't affect the spell, so he felt at ease in suffering those losses.
A few positive results happened as he became more experienced with the procedure. Still, Noah cut away those forged parts anyway since he wasn't satisfied with their power.
The experiments stretched on for an entire decade. Noah did nothing but training, sparring with Sword Saint, and modifying the Demonic Form in that period.
Then, when he finally obtained satisfying results, he entered the last stage of the experiment.
Noah couldn't allow himself to fail at that point. He was about to modify the core of the Demonic Form spell. Any mistake would damage one of his strongest weapons.
The First Kesier rune had the least number of roots, but the spell's core was there. Every effect and ability of the Demonic Form came from a thick root that gave birth to all the other ones.
Noah reviewed the procedure multiple times before approaching the First Kesier rune. He used the Divine Deduction technique to eliminate every flaw, and even his body reacted in the end.
'I will succeed,' Noah thought when he sensed his dark star spinning faster and improving his mental capabilities.
His determination had triggered one of the best features of his body. His star had reacted to the pressure that Noah felt when approaching the modification.
The thick root occupied Noah's vision. His ghostly figure floated in front of the First Kesier rune and called upon primary energy previously stored in his mind to begin the procedure.
During his experiments, Noah had found out that the dark matter was too heavy to interact with the roots without damaging them. The same went for his darkness, which forced him to use primary energy to perform the forging.
'Soft without lacking intensity,' Noah thought as a rune surged from the depths of his mental sea and reached the cloud of primary energy next to him.
The rune had a peculiar shape. It was a black spot with uneven edges that tried to spread in the environment.
That was the rune created to push the Black Mark spell to the sixth rank. Dark matter made its entire structure, but Noah had to sacrifice it at that time.
The rune fell apart inside the thin cloud of primary energy. Noah pushed the dark matter out of his mental sphere, but he restricted the meaning that it carried inside.
He didn't care about the rune. He could always make another one when he had the time. What interested him was the pure meaning he had managed to translate when he updated his spells.
The core idea of the Black Mark spell remained inside the primary energy. That thin substance initially ignored the influence radiated by that meaning, but it started to bend as Noah's containment continued.
With Noah there, even the volatile primary energy had to acquire special features. After all, he had become able to interact with the laws when he reached the sixth rank. He didn't need to rely on the native's inscription method to control the primary energy anymore.
The Black Mark's core idea became less intense as the procedure continued. The primary energy absorbed it and gained its features, which slowly turned it into the forging material.
When the meaning vanished, Noah approached the thick root and began the inscription. The modified primary energy flowed inside the Demonic Form's core, forever altering its fabric.
The root began to shake as Noah continued to pour primary energy inside it. Its branches became thinner as their core weakened, and some of them directly fell from the runes to disperse in the mental sea.
Noah continued without minding those repercussions. He knew what was happening, so the wilting of the roots didn't scare him.
Little by little, all the branches fell. Only the core root remained on the Kesier rune by the time Noah completed pouring primary energy.
The root shook. It shrunk only to grow larger again in a cycle that continued for minutes. Noah could only watch at that point. The forging was complete. It was up to the diagram to adapt now.
The root's color changed. It was already black, but the addition of that meaning made it even darker. Its edges became difficult to make out since light couldn't illuminate it properly.
The tremors eventually stopped, and the root remained still as if dead. However, it remained attached to the First Kesier rune, which made Noah confident in the procedure's success.
As if answering to Noah's confidence, the root slowly started to enlarge. It was a timid growth initially, but it gained speed as it became used to its new structure.
Multiple branches grew from the central body, and an intricate diagram quickly appeared on the six Kesier runes as the roots covered their surface. They even tried to spread on the Seventh Kesier rune's faint shape, but they failed as their predecessors.
Once the structure stabilized, Noah felt a surge of power filling his mind. Something inside him had already predicted the power of his improved spell, and the result made him feel ecstatic!