Lava

The ancient book automatically flipped itself to a page lit with four colored radiances. Of those four radiances, the red and yellow ones flew out and transformed into a light barrier that covered Lin Yun's body. 

The pages then flipped on their own until they reached a page that was flipping extremely slowly, as if it was weighing 500kg.

Lin Yun rapidly spat out an ancient rune into the Book of Death and that page completely flipped, exposing a new page.

That page was mostly blank, with three strange runes, but Lin Yun recognized them with a glance, this was the All-Encompassing Chapter.

It was only three characters, but it emitted the charm of the world, as if a world was being birthed there. The endless changes made it seemed like that world was containing anything and everything.

Under the four runes, there were two more strange runes, combined in such a way that it formed the rune for lava!