The place they were in was commonly referred to as the high-level battlefield by the combatants and the military personnel. And it wasn't without reason. It was a high-level plane, after all. And it was one that should be able to withstand the battles that broke out on it, so it was of decent quality as well, which meant that the plane's natural mana levels should be quite good.
After the war broke out, numerous combatants had entered the battlefield and fired off magic and aura with their mana before dying and letting all the mana in their bodies escape into the air. If the mana on the plane exceeded the plane's capacity to retain it, the mana would leak into the Void.
But it wouldn't drain the plane's mana reserve to the point where the mana below ground was weaker than that on a medium level plane. It wouldn't be noticeably strange if only the amount of mana were slightly different below ground than it was on the surface, but it was too stark a difference to claim it was natural.
And the war hadn't been going on long enough, nor had the battles been destructive enough to force the plane to use all its mana to begin healing itself. While it looked devastating, the damage on the surface was only slightly more than superficial. The plane would recover to its original state or even surpass it in time. It would take a while since all naturally existing life had been exterminated. But the mana that it had gained in the process of the war would be enough to more than enough to make up for the damage.
However, far from flourishing with abundant mana, the plane was suffering from a mana deficiency.
Toz was surprised and suspicious about the reason. There hadn't been any hints of the surface lacking mana, no matter where he looked. Toz quickly figured out that it wasn't natural, despite not being an expert on planes. Now he only had to figure out the exact reason.
If there were something sapping away half the mana from an entire high level plane, it would undoubtedly create a volatile variable in the war. The only questions were what it was and who it was that was responsible.
If it killed the plane, it might be something to do with the Tribe of Death. But if they were killing the plane like that, why not do it openly? Was it something that could easily be interrupted? Or was there another reason they didn't reveal it or use it on the entire plane, not just the surface?
Maybe the Tribe of Death wasn't responsible at all.
That meant there were two other parties that could be behind it, the Alliance of Kingdoms and the unknown group lurking behind the scenes with their plotting.
And between the humans who owned the plane and would stand to lose by draining it of its mana and the group, whose plans Toz was sure were nefarious, Toz was inclined to believe it was the mysterious group who was responsible.
As the thought struck Toz, he once again worried about Lucy.
If the ones plotting behind the scenes were doing something so monumental that it drained the plane of its mana, something really dangerous was bound to happen. But Toz also wondered why they had to go to such lengths. There had to be a reason why they used such an elaborate and demanding scheme that even required the mana of half a plane.
It might be nothing more than a precaution in case some other plane fails. But considering the lengths they must have gone to in order to proceed and keep it a secret from everyone on the surface, there had to be a reason or a demand for the amount of mana stolen from the plane.
Unfortunately, Toz wasn't able to figure out what it was with the few clues he had.
And that wasn't the only unfortunate thing. Due to the thin mana in the surroundings, Toz's passive training barely did anything except needlessly tiring his mind.
Without sufficient mana being pushed around by the moving wrinkles and creases of the layer of consciousness around his body, his mind was moving without doing anything. The empty actions strained his mind more than when he had more than enough mana around him.
It was an unexpected discovery, and Toz directed his thoughts to why it was like that instead of worrying endlessly about Lucy and the conspirators and their conspiracy.
However, he didn't achieve much progress on that front. And he didn't want to waste too much effort or sink too deep into thought at the moment. He was still in the middle of a top-secret mission with a maximum risk of death. Exhausting himself or getting distracted could get him, the cats, and his allies killed.
Toz could get over the guilt of getting his allies killed after some time. But it would be a lot harder to get over getting himself, or even worse, the cats killed.
So after letting his thoughts wander as they wanted for a little while, Toz resharpened his focus and concentrated on keeping an eye out on their surroundings and having his mana at the surface of his body, ready to lash out at less than a moment's notice.
His mana vision didn' penetrate far into the thick walls of earth, barely a meter. Braxton could probably detect at a far greater range than that. But Toz didn't want to take any chances, especially since he had already proven on several occasions that his mana vision was far more sensitive and accurate than most others' senses. At least regarding magic and mana. Mana vision only worked on physical objects because Toz also used his eyes when mana vision was active.
There was also the fact that seeing something with mana vision for himself would be more reliable than listening to Braxton, especially if the situation devolved into chaos, something that could easily happen, considering the nature of their business.