Minasian Sorcerers cannot sense or detect the enclosed barrier erected by the System, and it is mostly thanks to the System itself, for they are not players or candidates to become players in the future.
Only players and candidates to become players can see and interact with the System.
Even so, Minasian Sorcerers can still take down the erected barrier if they have the might or power to do so, magically or otherwise. Unfortunately, none of the people here has the power to do so, at least from their current power level.
Sure, there is a possibility that one or more might be hiding their actual power level, but they have to be fairly powerful to destroy the barrier in a single shot – that is one sure way to take down the barrier.
Another sure way is to kill me. And killing me is far more harder than just destroying the barrier itself, which is already incredibly difficult.
They can still damage the barrier by attacking it directly, however. But any damage done to the barrier will be instantly negated as long as I have money.
And I do have a lot of money for repair.
"I cannot sense any mana from the barrier at all!" one of them calls out and immediately redirects his attack at the barrier, and the barrier flares out as bolts of energy impact repeatedly against it. "There is no fluctuation at all!?"
For any sort of barrier, fluctuation means that it can eventually breeched, but to sense the fluctuation, he must be able to sense the barrier first. Since he cannot sense the barrier due to him not recognized by the System, he cannot sense the fluctuation.
In contrast, I can, and the barrier does fluctuate a little from withstanding the magical bolts.
"Let me help you, brother!" another of the intruders calls out and strikes at the barrier alongside with the other, but even their combined attack does very little damage to the barrier.
"You are just wasting your mana," one of them comments and eyes me. "We are trapped in some sort of formation, and with our current power, the only way out is to kill the Formation Master."
I match his gaze, and I cannot help but smirk slightly. He is right, and he is obviously not an Apprentice Sorcerer for him to know that fact. He is also the only one amongst the intruders who has not tried to do anything pointless yet.
"Formation Master? That brat? You got to be joking, brother," another person retorts, and just like an idiot, he continues to attack the barrier, wasting his mana.
"I don't think he is one, but his master might be," the first one points out. "And for him to form a Mana Sea at his age, it is not just a remote possibility. His 3rd Grade Magic Weapon as well. Also, his strange Magic Array… tell the others to stop."
He then claps his hand together and gives me a slight bow. "Looks like we have made a grave mistake, and we are willing to drop this matter if you let us go."
I match his eyes as the Magic Array in front of me completes, and the moment it does, it radiates and hums with incredible power. I only need to activate it in order to unleash a Tier 4 Spell.
And there is no need to hesitate, as I activate the Magic Array verbally. "Mana Drain."