The Dark cover spell made use of the natural darkness of the night to cover the figure of the cultivator casting it.
Noah had never relied on it because of that restriction and the limit to the power of its diagram.
However, the appearance of a rank 6 creature in the area that he needed to explore made him reevaluate his priorities.
The modifications on the Dark ray spell had been almost completed, but Noah didn't need it right now.
He could always pick up from where he had left in the future.
Yet, now he needed something that could allow him to fly unnoticed through the mystical fog.
Of course, he knew that a normal spell wouldn't be able to deceive the natural awareness of a rank 6 beast, but the conditions in that danger zone were quite favorable to him.
The fog naturally affected the perception of the living beings living inside it, and the Fog demons weren't an exception.
Also, the senses of the specimens of that species would be further limited when the gaseous armor surrounded their real bodies.
The Fog demons were able to thrive in the mystical fog, but they were still a weak species, any expert in the magical beasts' field would be able to exploit their weaknesses.
Noah already had a few ideas on how to modify the Dark cover spell.
He had completed the translation of its diagram during his travel, but he couldn't rely on something that could only be activated during nighttime.
Luckily for him, the Cursed dragons naturally absorbed the light in the environment to nourish their lungs.
That feature created a constant dark halo around their bodies, and Noah wasn't an exception.
'Instead of the darkness of the night, I need to make use of the darkness created when I absorb the light around me.'
That was Noah's idea regarding the modifications needed to improve the Dark cover spell.
Noah reached the Scarlet mountain chain and chose one of the seemingly empty mountain peaks as his training area.
Chasing Demon's task didn't have a time limit, and he didn't mind focusing on his spells for a while now that he found a situation that required them.
The first step in the modification was to alter the structure of the will created when Noah translated the diagram.
The tricky part was that the original spell made use of the natural abundance of the darkness element during the night to fuel its effects.
Noah could keep that feature, but he also wanted to create a way to make use of the spell during the day, which meant finding a different source of darkness.
The natural dark halo that surrounded him wasn't enough to match the night, but Noah could make up for that with the "Breath" inside his dantian.
That approach would make the final product a bit more expensive for what concerned the energies needed to activate it, but it would be worth it if it made Noah able to take by surprise cultivators on his same level during the day.
The next hurdle was the expansion of its limits.
Noah needed to spend a lot of time finding the right method to push the power of that translated diagram so that it could become useful in the fourth rank.
He couldn't just stretch the meanings contained in his will, and he also needed to reestablish the previous harmony once he improved its power.
The difficulty of that task though couldn't match that of the translation and modification of the Warp spell.
Every diagram was simple compared to a spell that could accompany a cultivator through the entirety of its journey.
It took Noah a little less than four months to complete the modifications to the Dark cover spell and perfect its harmony.
A dark but void human shape hovered over the sea inside his mind when the process was over.
That was the new form that his spell had taken after all the improvements.
'This should allow me to fly through the eastern part of the mystical fog without alerting its rulers.'
Noah evaluated when he analyzed the will and decided that it was time to resume his exploration.
He returned in the danger zone that divided the areas of influence of the two big nations, in the spot where he had first sensed the rank 6 creature.
That oppressing presence was still there when he returned there, it seemed that the creature didn't move at all during those months.
Noah quickly fueled the will inside his mind with the energy contained inside his Liquid dantian and mental energy.
Part of the will was consumed during that process, but a dark layer slowly formed over Noah's skin and covered the entirety of his body due to its effects.
The dark layer was formed by the darkness that his body naturally created and the "Breath" in his dantian.
However, the spell was fueled by his mental energy and Liquid dantian.
That allowed Noah to push the power of the spell to the solid stage without emptying his dantian.
The layer perfectly adhered to his body, Noah was barely able to notice it.
Yet, he could feel that his presence was somewhat faint and that his figure radiated an even darker halo.
He wasn't invisible, but a cultivator would only able to see a black spot in broad daylight.
'The effects are similar to Elder Julia's hiding methods. I should still avoid entering the line of sight of the beasts and cultivators if I want to surprise them. However, I can go completely unnoticed in environments similar to this.'
Noah nodded when he thought that.
The new Dark cover spell turned out to be a situational ability even with all those modifications, but Noah was satisfied with it.
Perfect abilities didn't exist, cultivators could only have a set of skills that could give them an advantage in every situation.
Noah resumed the exploration of the eastern side of the mystical fog after he activated the spell.
He still increased his height when he flew over the area where the rank 6 creature was staying.
There was a limit to how much a spell could do against such a powerful being after all.
The exploration continued peacefully, and Noah even found the chance to kill another rank 5 Fog demon in the lower tier at some point.
The Dark cover spell lasted for a few hours, so Noah was forced to reactivate it whenever its effects began to wear off.
Nevertheless, that wasn't an issue, those hours were more than enough to refill his centers of power.
Noah began to think that even the eastern side of the mystical fog didn't contain any clues of the two demon sects since he was about to reach the east coast of the old continent.
However, it was at that point that he noticed strange lines on a random spot on the ground.
The lines didn't shine, but they were part of some sort of formation, and Noah didn't hesitate to analyze them.