An hour after all that perplexing twists and turns of events, Eli finds herself still immensely bewildered and disturbed by everything.
It takes that whole hour for the three of them to make sense of the aftermath and all the details that led to it.
Venus explained to her how exactly she ended up getting caged by that sphere of crystals. It just happened that Aion went after Eli without any of them noticing, and as soon as the former Empress sensed danger coming her vessel's way, a new summoned creature made an entrance out of nowhere.
Realizing how she's starting to lose consciousness after Aion sent her back in time, Venus immediately made Eli use her crystal magic to form a barrier that could protect her before that white-haired villain could get a hand on her. Hal is still occupied by the other summoned creature at that very moment, which is why she needed to take that action.
