Currently Alex was in the fourth floor and finally he get to know the danger of this world tower. Well in those previous floor he did not face this kind of danger and he could easily kill those Monsters present in that floor but the monster in the fourth floor are really different.
Currently Alex went to the danger zone to face Monsters and as you know that he was the first one to came to this floor he did not have anyone as his teammates no did not want to make any team. So he came solo to kill Monsters but who could have expected that the first monster he will face will be a S-grade monster. But also the most dangerous thing was that the monster wasn't alone, it also brought 4 more monsters with him.