Thankfully, it wasn't long before Rui got his hands on what he needed. The Beggar's Sect did not inquire into how he intended to use them, but he did not forget the stare from the professor as he left the Libraries of Gehu before heading to an uninhabited location where he could train without being spied on, a location he got from the Beggar's Sect as well.
Deep within a cave network in a mountain range in the Derschek Region, Rui sat down as he worked with the new toys that he got from the Beggar's Sect.
There were many parameters and phenomena related to sound that he had yet to explore. Techniques like Transverse Resonance make use of constructive resonance and superposition between two sound waves to overlap two sound waves into a single stronger sound wave.
However, there were other phenomena that could be used as the basis of new techniques.
Rui activated his Martial Heart, never once taking his Mind Mask off, before firing off a Mighty Roar Flash Blast.
THWOOM!
BOOM!!
The attack annihilated half a large hill in the distance, leaving a cleaved structure standing with its other half missing.
However, it wasn't the destructive power he was paying attention.
"Tsk," Rui tutted. "Too attention-drawing."
His senses and sensory techniques, when passively empowered by the Martial Heart were able to detect the sound wave.
This was without the Riemannian Echo technique, too.
Furthermore, this was with a younger and weaker Martial Heart.
Senior Sarak had already informed him that Martial Seniors could tap into the Martial Heart with techniques to empower those techniques. This meant that Martial Seniors with passive sensory techniques could not be truly caught off-guard since those sensory techniques could always be active, and thus were always tapped into the power of the Martial Heart passively.
He himself had the same ability with Primordial Instinct. No Martial Squire assassin could catch him off-guard because Primordial Instinct was always passively active, and passively empowered with the Martial Heart.
It was one of the reasons he had easily been able to foil a well-hidden assassination attempt with ease despite the stealth techniques that the Martial Squire assassin had employed.
Unfortunately, it worked against him when he wanted to assassinate Martial Seniors. By the Senior Realm, he was certain that pretty much every Martial Artist had at least one sensory technique. Even if they didn't before, when they realized how dependent they were on the Martial Heart, they would master at least one sensory technique that could passively be empowered by the Martial Heart to ensure that they would be able to better sense incoming ambushes and activate the Martial Heart in time.
This meant that Rui's previous thoughts were right. The Mighty Roar Flash Blast technique was no longer an effective covert assassination tool against Martial Seniors. Unless there was a foolish Martial Senior out there who had yet to master a single passive sensory technique, Rui could forget about relying on it to easily assassinate his targets.
A Senior-level attack was too powerful to hide from them.
However, as Rui had come to realize, that only applied to Senior-level attacks. Weaker attacks were harder to notice since they had less energy.
Rui carefully adjusted the power of the attack to half, before firing again.
THWOOM
'Still too easy to sense.'
Thwoom
'Better, but still far too attention-drawing.'
He continued significantly reducing the power of the Mighty Roar Flash Blast technique before finally reaching a stage where he couldn't sense the attack after it moved further than ten meters away.
There was one predicted problem, however.
'These attacks possess less than three percent of their original power.' Rui sighed.
This was the price of making it undetectable; making it incredibly weak, so much so that it had entered the Squire Realm. Martial Seniors were easily quasi-Senior level even without the Martial Heart, such attacks were not a threat to them even if they were too weak to be detected.
This was the predicament in which Rui found himself.
If he made sound attacks strong enough to kill Martial Seniors without their Martial Hearts, they would become too strong to be undetected.
If he made the sound attacks too weak to be detected, then they were also too weak to kill Martial Seniors.
He highly doubted that he was the only Martial Senior to stumble into this predicament. Sound was not too rare as a form of offense at his level. There was a reason that Martial Seniors were not assassinated left and right all the time, there were many practical constraints that prevented Martial Seniors from assassinating their peers too easily.
However, Rui was not content with abiding by this restriction. He needed the power to assassinate his peers with unerring success. Unlike his peers, perhaps unlike anybody in this world, his theoretical understanding of the nature of reality was better than any of his peers.
On a theoretical level, he understood sound much better than even Xanarn. He recalled how shocked and dumbfounded Senior Ceeran was when the man first learned about the Pathfinder technique and its complex mechanics. It had taken him eighteen months and much handholding from Rui to master the most elementary version of the grade-ten technique.
Rui had had much evidence in his time on Gaia to know that his scientific background gave him huge advantages over his peers.
Impossible hurdles that impeded his peers were not so hard to overcome for him. It would not be the first or the last time since he accomplished such a feat.
One of the reasons that he had begun focusing on pitch training was to test a hypothesis. A potential means by which he could overcome this hurdle. As he continued training his ability to identify and replicate pitch, his mind flashed back to a memory in his mind a long time ago back on Earth.
A teacher had put two tuning forks on a table at a distance from each other, before banging a metal rod against one, causing it to vibrate significantly. Magically, the other tuning fork also began vibrating energetically all of a sudden.
