With Henry's power level, it was quite easy for him to be able to kill the monsters within the dungeon. But of course, he simply limited himself in order to make sure that the mage profession leveled up as fast as possible.
But even when he was utilizing only a single skill, the speed at which he was killing the monsters was terrifying. Had it been that Olivia and the others were here to observe it, they would definitely feel a chill running down their spines.
But even then, Henry simply continued killing the monsters, trying to level up as fast as possible. The amount of energy that he possessed was not a problem. Not to mention that his energy reserves were quite big, but even if the energy that he possessed was depleted, he would simply take the recovery potion, and he would be able to recover to his peak condition.