Gravis needed to use all of his Energy to resist the heat. If he also had to resist the gravity, he would waste far more Energy. Because of that reason, Gravis told Morus to stop. This depth was perfect for him.
"Remain like this and tell me if it becomes difficult for you to keep me from falling," Gravis said.
"Yes, Master," Morus answered.
With that said, Gravis closed his eyes and concentrated on the feeling of gravity.
Right now, the gravity was so terrifyingly powerful that some muscles and organs even ruptured from time to time. His tail especially was tearing a lot since it held Gravis' entire weight. Thankfully, Gravis knew several Life Laws, which made it possible for him to remain in this state indefinitely without running out of Life Energy.
