"Just try to grab hold of the stone with your mind," Gerald said. "Oh, and you probably need your Magic Eyes to do that, so Elly and Blum, you probably won't be able to do it…"
The three already knew what Magic Eyes were since they experienced it, and for the rest, it wasn't important. still, it didn't hurt to try.
"Oh, okay…" Sera was the first to try it. She extended an invisible tentacle-like Mana arm and tried to grab the piece of stone floating in the air. However, as she came closer, she felt it was getting harder and harder to keep it stable. It was as if her mind was actively trying to sabotage her, making her control crumble.
She became red in the face and as the 'tentacle' approached the stone, and at half a meter away it just couldn't continue. Any movement forward would make it disintegrate, almost as if an invisible barrier was preventing it from advancing.
Gerald encouraged her to continue verbally, but he knew in his heart she couldn't succeed. He already figured it out a while ago, but the Aura he could see would also prevent others from using magic directly on a foreign body.
That was, of course, if they were both at full health and about the same strength. A powerful being could simply ignore the weakling's attempts at stopping them, just as Gerald ignored Eneth's feeble grasp.
Then there was the consciousness dilemma. If someone was sleeping or unconscious, their passive protection would be way weaker. One of the rare examples was when Gerald was in a coma and Tabbris could easily use his Ice magic on him.
When the mind was asleep, the body was unguarded.
If a person knew what he was doing, he could expand or contract this Aura to various effects. He could retract it and let others heal him or perhaps extend his aura like they were doing now in an attempt at stopping the other caster from completing the spell.
"Huff, this…is impossible!" Sera huffed in exhaustion after a while. Streams of sweat ran down at her temples.
"You are forcing yourself too much, focus with your mind, not your body," Gerald said. He noticed her control was still weak. She still placed too much of her focus on her body instead of it being a 100% mental effort.
"Okay, next!"
Xilia stepped forward and tried it out. She appeared way calmer and composed on the surface, and barely any changes showed on her face. It was as if she was simply looking at the stone, nothing else.
However, on the inside, she was cursing loudly. The stone before her was like an unmoving mountain, and she couldn't budge it no matter how hard she tried. The funny thing was that the stone wasn't still in reality. It was gently swaying in the wind, almost as if it was weightless.
She almost felt like the stone was taunting her, it was extremely annoying.
Elly didn't do much better. Her face immediately became red and veins almost popped out of her face as she exerted herself, to no effect, of course.
Eneth didn't even try to take the Stone Bolt back as he already had the painful experience, while Blum was quick to surrender after realizing he was no match for Gerald's might. Out of respect for his boss, and also because he didn't want to waste his energy for no reason, he decided to simply try it out for a few seconds to get the feeling of it, and then stop.
"Alright, good, now you have all experienced what a stronger opponent can do, or how hopeless you are against him," Gerald said, totally not boosting his own ego.
"Now let's try again, but this time I'll adjust my strength to mirror yours. Sera, would you like go first?" he invited.
"…Sure, I guess."
As she exerted her mind this time it resulted in some actual changes. The stone shook and slowly, with great effort on her part, Gerald's grip loosened and she took control.
"I did it!" She shouted triumphantly and took the floating stone closer. Her face told of her exhaustion, but still, she wore a bright smile nonetheless.
Gerald clapped his hands, "Excellent! It seems that 0.1% of my strength was just about right… Okay, who's next?"
"...Wait, what?!"
"Me, me, me! Pick me!" Xilia jumped up and down and waved her hand.
They went through the exercise again with each mage participating once. After they all successfully grasped the technique, Gerald urged them to train among themselves and so they did.
It was almost like a football game, they just had to snatch a stone instead of a ball from each other. And instead of using their limbs, they used their minds.
***
The rest of the warriors that weren't participating went back to the wall and helped defend. Although Goblins couldn't cross the barrier alive, that didn't mean the rest of the monsters would be the same.
Hobgoblins could force their way through, although not without severe burns, while the Orcs and Wargs they were riding could swiftly get across, sustaining only minor injuries to their skin.
Some warriors that were fighting on the other side before the barrier formed were almost all dead. When their path of retreat was cut off, they were on the mercy of the beasts.
Some had mage friends who created rings of ice or stone through which they could jump back inside, but most weren't so lucky. In panic they rushed back, resulting in being burned alive, or torn apart by monsters when they turned their back on them.
An outraged mob was formed after many of their friends were brutally murdered, and the warriors couldn't even vent their anger since nobody knew where the barrier came from and who was responsible.
In some other places, people celebrated the barrier as it came just in time as they were getting overwhelmed, and gave them a few precious moments to take a breather.
There the casualties were already high, and the sudden Flame Barrier helped mitigate even greater losses.