Here Reigns the Vengeful Villainess - Chapter 78

This is actually one of the most interesting scenarios that is recurring in a lot of these stories, the only way that they were successful in destroying the celestial custodians was specifically because celestial custodians were not a threat or enemies. The only way they were able to kill all of them was by relying upon the love and trust the Celeste all custodians had for them to poison them. Like if they were truly beings to be feared then they would never have been killed off by poison handed them by somebody else.