Collect the cores..?

My summons and I are able to make fairly quick work of the first wave of monsters on the 1st floor.

Already ten minutes have passed since the wave began. Contrary to what I expected, there was nothing special about the wave. It was the same old battle between monsters, except this time, the opponents were people.

In all of their Camps or tunnels that lead to the surface, human soldiers have put up barriers to prevent monsters from reaching the surface.

I was amazed at how easy it was for them to kill the monsters. By joining together 100 Knights, they formed a barrier that completely blocked the entry of all monsters.

As the monsters continued to attack the barrier without gaining any ground, the mages and archers fired their spells and arrows through the air at their enemies.

It was a genius of a spell. An entry barrier that rejects attacks from the outside but allows them to pass from the inside. Only hum