The first thing Rui needed to do was find the right location under the nineteenth floor. This mattered a lot and would greatly impact his chances of getting away unscathed. The bedrock of the lake was not evenly thick, thus it was probably best that he looked for the place where it was thickest.
Aiming for the thickest part of the bedrock may end up being the hardest and most time-consuming, but it would certainly be the safest. Thus he needed to pay attention to that, among other things.
On top of that, he also needed to pay attention to the tunnels in the vicinity of the point where he was hoping to break through. If the tunnels all lead downwards, then that point was unsuitable. What he needed was a place where there was a route upwards as well.
The reason for this, of course, was the fact that the released water would rush through the tunnels and go downwards. Thus, if there was no way up, Rui was screwed and would need to spend quite some time in a wild escape for his life until he got far enough that the water would not reach him or found a way back up that wasn't flushed with water.
Thus a tunnel in the immediate vicinity leading him back up was definitely very important to him.
Another condition that the hole he would create needed to satisfy was that it had to be at the lowest points of the lake. If it was too high, then there would be a portion of the lake that would not get drained due to being lower than the hole.
On top of that Rui also needed to take into account the debris that he would be creating by blasting a large hole across the bedrock relative to the size of the tunnel. He needed to make sure that the debris did not block off the tunnel, nor did it raise the height of the tunnel such that the distance between him and the hole was reduced.
Water would travel faster through a narrower tunnel, and that was not good for him.
A multitude of variables was within his consideration as he picked a tunnel downwards, scanning the tunnel network below the nineteenth floor with his Riemannian Echo. Going down would allow him to sense everything better.
The lake was surprisingly deep for its size. It was almost closer to a trench than it was to a lake, from his perspective.
('That's going to make the water blast out with even greater speed,') He murmured unhappily. Height corresponded with more pressure at the bottom, which corresponded with the speed at which the water would blast out.
Still, he wasn't too concerned. The reflexes of a Martial Squire, when prepared, were quite remarkable. Although the water would blast out at an incredible speed, he was not going to get caught unless he was truly unfortunate. What he was most careful about was the initial moment of breakage.
Specifically, he needed to make sure that he timed it right, and was not caught off-guard. Furthermore, he needed to make sure that it was large enough on the very first shot, otherwise, he would need to escape even if it wasn't, and would be forced to waste too much time
He also needed to keep in mind that he could just peacefully go on hacking at the bedrock whistling away. The lake was also exerting a tremendous amount of pressure on the bedrock from the other side of which Rui was on. Meaning, at some point, the lake's own pressure would be enough to crack open a hole, he needed to ensure that it would be big enough.
('On top of that, I need to make sure that my attacks are sharp and precise. Else it is liable to cause cracks that will start leaking large amounts of water ahead of time,') Rui sighed. ('This is starting to become more of a pain than I had imagined it would be when I initially conceived of the idea.')
It took him longer than he expected to finally settle down on an idea spot after extensive searching and filtering. He found a single spot that suited his needs.
STEP
"Hmm…" He inspected his surroundings when he reached his chosen spot. "Good thickness, large tunnels, and straight tunnels where I can reach a high speed, and a decently close path upwards to avoid the water."
He glanced up. "Thirty-six meters… give or take. Just barely large enough it should work."
He heaved a sigh as he prepared himself. Breaking a ten-meter wide hole in the lake was the bare minimum in order to drain the lake in a reasonably short timeframe. If it was much smaller than this then it would take far too long to drain the lake. Rui risked the lake being found by other adventurers which he most certainly did not want. He definitely wanted to cleanly finish it before any external entanglement could complicate matters.
He was even warier of other Martial Squires after his fiasco on the sixteenth floor with Chairman Deacon's raiding team. The man had no doubt taken the time to form some measures that hoped to replicate the stroke of good luck of having Rui and Kane detected that day.
He closed his eyes as he gathered his focus. He breathed deeply as he honed his mind, gathering his focus and concentration.
"Let's begin,"
He pulled out his hot air pipe. Although Transverse Resonance was a sound-based technique, not a wind-based technique, it was still best to heat up the initial air particles of the sound attack, even if most of that heat was lost in transit.
He inhaled air from the hot air pipe deeply, before facing up.
THWOOM THWOOM!
He shot two rapid sonic blasts one after the other, the second being considerably faster than the first one. The two sonic pulses overlapped in constructive resonance as they merged into a single projectile of sound.
BAM!!!
The first sonic projectile slammed into the top of the tunnel, causing a huge crater.