After defeating a horde of the Ba'al's Invaders and STMC, Nia throws you into a warp hole which causes your group to end up in Paradigm City. There, Gadright of the Geminis has used some clever words to push Angel and her desire for memories to seek out the truth beneath Paradigm City. She ends up becoming Big Venus, a mysterious Big that was somehow involved in the events of 12,000 years ago.
While you are fighting Mykage, Big Venus makes its appearance while Gadright taunts you. Gadright knows that Big Venus is capable of erasing anything from existence and with it unleashed, it will certainly erase everyone on your team and even the earth. With Mykage on one side and Big Venus on the other, it seems the Ba'al have you defeated within an almost perfect pincer attack. Roger, however, recognizes that Angel is in Big Venus and tells everyone of his desire to negotiate with her. In fact, it may even be your only hope considering there may be no other way of dealing with an enemy such as this. Everyone complies and believes in Roger. Bright even gives orders in support of Roger.
Anytime someone on your team attacks Big Venus, regardless of whether it even hits them or not, will be erased from existence. I included a small set of encounters just to show off the dialogue where most members of your team will more or less state how much they trust Roger to deal with this situation. Thankfully, after Big Venus has been beaten and Roger gives his monologue from the finale of Big O Season II, anyone who has been erased will be restored into existence.
Note that this was done on the Secret Route, so it is possible the events occur slightly different on the Normal Route.