Following Azulon's submission and after witnessing the battle, most people had a general understanding of Merlin's abilities. Thus, many people were eager to join Merlin's squad.
Nevertheless, it was not easy to join Merlin's squad. All of them had to offer their bodies and must not resist to enter Merlin's world. Due to Merlin's special abilities as a Controller, he could communicate with everyone and amass their powers to detonate an unparalleled attack.
If not for this life-or-death juncture as well as the repeated assurance from a few Major Cosmos Absolute Beings, no one would trust another person to enter their world. This was because once they had entered it, they would have to endure a massive suppression and entrust their lives to the Controller.
