Core formation

Liam started going through one manual after another while sitting inside the stone tablet pocket world. He already attempted gathering more herbs using the stone tablet but he was only able to get A-grade herbs and below.

Even though the B-Rank world's mana density was extremely high, the natural mana density was still not enough to fuel the stone tablet to produce higher-grade herbs.

There was also something else that happened. 

Liam had assigned a few of his soul minions to stand guard while he was inside the pocket world and these minions told him that there was a small mana swirl in the pocket world's location or rather the location at which he had used the stone tablet.

So if someone really powerful were to attack that spot, they perhaps would be able to break and get through to the pocket world and attack him when he was meditating and vulnerable.