Chapter 118 - Mega Fireball

In the association, 

Markus, Vena, Mira, and the others were observing on the screen where the screen showed the students. 

They already saw that Maria and the others were defeated by the monster. Fortunately, the monster knows that even if he can defeat them, he won't be able to kill them. Because of this, he let them go and bounced out of the cave. He needed to absorb the life energy of the warrior whose blood the enemy used in this pattern. He didn't want to delay this.

If you are thinking about the enemy, then Alena already killed the enemy with her sun ray. When they can kill the enemy, they thought that they successfully stop the summoning process, but we have thought that they won't be able to stop the summoning process.