All the Time in the World

Gary stood in front of the weirdest portal he had ever seen in his life. Normally, a portal would be completely covered in swirling energy with hazy light coming off of it, and would not allow one to look into what was inside of it.

However, this new dungeon that had formed out of nowhere had a portal that clearly showed what was inside.

He looked at the reading on his device and was confused by the findings as well.

"Why is there absolutely no mana in there at all?" he wondered. His head ached from the lack of sleep as he was forced to look after the dungeon. He wanted to sleep already, but he would have to wait a while since he was going to send some people in to check the inside.

The group of hunters, the one at the head of them all being an A-ranked one, walked inside immediately. 

Gary had to wait around 3 or so hours before they completely cleared the dungeon and—

"We found nothing," the leader said from in front of him.