Cultivation

Dante was speechless. That was as good as not saying anything. He rubbed his forehead with tiredness and glanced at the other closed rooms where Humphrey and Slessor were probably absorbing as much Zero Energy as they could to empower themselves and increase the Rank of their superpower. 

Dante also checked the time with his AI and saw that it had been only an hour since he entered here, which meant that he had been absorbing the energy himself for around that amount of time. 

Yet, he did not feel anywhere near sublimation in that regard. He glanced at Xue Bing and asked tentatively. "How long does it take to go to the D Rank from the E Rank after the initial upgrade from the F Rank?" 

Xue Bing contemplated for a moment before responding. "The time required to advance from the E Rank to the D Rank can vary depending on the individual and their level of Potential and the nature of their superpower."