Pain

Alex got into the artifact after filling it with as many Spirit stones as he could. He had placed enough so that the artifact would run for over 2 days easily.

That was how long he wanted to cultivate. 

Inside, he was surrounded by the pieces of rocks that he was using himself today. He could've used any sort of materials he wanted. It didn't just have to be rocks, but it could also be glasses, metals, wood, ceramics, anything.

As long as it was hard and somewhat sharp, it could work. However, no matter what materials it was that the book told him would be useful, Alex didn't believe it would be any more useful than what he had used already. 

He had currently access to exactly 3 things. The first were normal rocks that Whisker had been using, there was no way he was going to use them, so they were out of the picture.