Eclipse Cult's Old Ritual

[So that old tradition still lives. . . Alice, I believe this kid is part of an. . . Old ritual. Similar to the one that Ria was part of but more brutal.] 

'More brutal??? Than Ria's???' Alice paused in surprise. 

While she didn't know the full details of the ritual that Ria was involved in, what little information she had was enough to tell her of the brutality of the Eclipse.

How they treat lives as nothing but material for their next ritual.

Yet despite knowing what Ria had gone through, Cayla still said that what Jin was a part of was even more brutal!

[The purpose of this old tradition was to cultivate vessels that could act as anchors for the Apostle's power. Mediums for them to channel and use. In short, it turns whoever 'survives' the Ritual into a one time use expendable item.