Firey was thinking about the primal magma while Himmel Soan's mind was on something else.
He was thinking about his original group members. He had saved them once. The last thing he wished to see was them dying here, but there was nothing he could do. They were on their own.
Maybe they had found another way to avoid this obstacle.
Himmel Soan stopped worrying about them and went on soaking in the magma, which helped with his recovery. It was the same as absorbing spiritual essence.
...
Above them, the demons didn't notice anything because none of them was in the mood to look around. After all, the magma could kill them instantly.
They didn't want to watch death in the face. The magma alone almost forced them to flee. Therefore, no one noticed Himmel Soan and Firey.
"I guess this is it," said the bald demon.