Feeling the Tug, Lin Mu became alert.
He knew that if something could pull on his spirit sense even now, after being refined this much, there must be something strong behind it. Lin Mu very carefully let his spirit sense descend even more, but realized that the tugging force was getting even more strong.
"Damn, if I let it go further, it will just end up ripping my spirit sense." Lin Mu understood.
"What did you find?" Little Shrubby asked, seeing Lin Mu's reaction.
"I don't fully know either. But whatever it is… it can pull spirit Qi of any kind, it seems. Even if it is in the form of spirit sense it seems to be strong enough to pull it. I think that is also why there is no spirit Qi in the area." Lin Mu replied.
Little Shrubby tilted his head in confusion and looked towards the bottom. After a few seconds, he spat out a small ball of fire towards the bottom. Lin Mu and Little shrubby then saw the ball of fire falling towards the surface of the hill.
The place where it fell was scorched a bit, but then the ball of fire started being sucked into the ground. Seeing this Lin Mu and Little Shrubby, both raised their brows. One must know that the ball of fire had enough spirit Qi to continue burning, even if it fell on the ground for at least a minute.
Thus, it was not just normal fire that would be extinguished like that. Instead, the ball was pulled into the ground easily. Lin Mu followed behind it with his spirit sense and saw that the ball was transformed into a drop of fire elemental spirit Qi anal quickly pulled to the bottom of the hill.
The Eight hill was just over two hundred meters tall and thus the maximum depth that Lin Mu haha reached with his spirit sense was just half of it.
"This is certainly very strange. What could be sucking all spirit Qi like that? Some beast, or some treasure perhaps?" Lin Mu wondered.
"The location from where the former adviser Chu left. Was it close to this place?" Xukong asked.
"Yes, senior. It's there," Lin Mu pointed towards a pair of hills.
The hills were very common looking and would hide very well in any background. But if one looked closer they would find a small black patch between them. This small black patch was actually a large boulder that was blocking the entrance to an underground cave.
"So that's where he hid the formation array, huh… I think this place and that might be linked." Xukong said.
"Huh? How so senior?" Lin Mu questioned.
"Why don't you go down to the bottom of the hill and see. Check what's hidden beneath the ground." Xukong replied.
Lin Mu nodded his head and agreed.
"Just wait here, I'll go take a look." Lin Mu said to Little shrubby.
"Okay," Little Shrubby replied, and spread his spirit sense around.
He knew now to keep an eye on the surroundings seeing just how many beasts there were in this place. Even Dao Shell realm beasts could pop up at a moment's notice and thus it was better to keep alert.
Lin Mu then sank down into the hill using phase and kept on freely sinking. In just five seconds, he was at the hundred meter depth.
"This is where the suctions force got stronger." Lin Mu said as he very carefully extended his spirit sense.
He made sure to not let it go beyond ten meters, as after that, his control over it would weaken under the suction force. Lin Mu certainly did not want his spirit sense to get torn here.
"Hmm… nothing here… need to go deeper." Lin Mu said and sank down further.
Soon he had reached the same level as that of the hill's base. He could be said to be at the ground level now.
"Damn, the suction force is even stronger." Lin Mu said and retracted his spirit sense to only a five meter range.
But even here, there was nothing for him to find. He wandered around in the hill searching for the source, but did not find it at this level.
"Do I really need to go deeper?" Lin Mu muttered.
Gritting his teeth, he sank down even more deep. This time, he slowed his speed and kept an eye on the suction force. The force kept on increasing more and more, and became the strongest at about fifty meters below ground.
At this point, Lin Mu could not release his spirit sense from his body at all, or it would get torn.
'Bah! May as well see what's even deeper.' Lin Mu thought to himself and went deeper.
But here was when the things changed. The suction force actually decreased here and by the time he was a hundred meters from the strongest suction point, it was completely gone, allowing Lin Mu to freely use his spirit sense.
"Huh… what the…" Lin Mu was now confused.
He had thought that something would be hidden beneath the area with the strongest suction force, but it was nothing here.
"See… I told you it might have something to do with the cave. Go back up and follow the area, it should now be moving in a horizontal manner instead." Xukong suggested.
Lin Mu did as was told and went back up and moved horizontally toward the direction of the cave.
"This is like a tunnel… but for spirit Qi." Lin Mu understood.
"Mmmhmm, it might actually be a formation array." Xukong said.
"Of course! With a suction force as strong as this, barely anyone would be able to prove it without hurting themselves. No wonder it could stay hidden so well." Lin Mu understood.
"This is one of the more complex methods of hiding a formation. But to more experienced masters, this is also the quickest way to find such formations." Xukong replied.
Lin Mu nodded his head and followed the 'tunnel' all the way to the cave where the former adviser had escaped the Sinkhole from.