Egg?

The duration of the Skill, 'Reinforce' has already ended. It still needs another twenty-six minutes before Ban could use it again. 

However, Ban did not think too much about it. They already killed the first wave of the Two-Tailed Rats, and even though they still expected more, they knew that the rats numbers would not get past one hundred as well. 

"Let's go, Eva!" Ban said in his unusual voice that has been modified by the Ant Mask that he was wearing. 

If it was any normal Summoner and 'Monster' they would surely be already tired after fighting that intensely without rest. However, with the passive effect of the skill, 'Greed', the Absorber, his and Eva's energy were getting replenished every time they kill a Two-Tailed Rat Beast.