I begin the video at the final save spot in the outer dungeon at excited Conficts fate. This is the place right before your encounter with the many forms of Cubia. From here I engage four Cubia Alphas and one Cubia Beta in avatar form.
After Haseo rams his avatar down Cubia's throat, you are faced with a winding road up to the core. At every interval you must fight against doppleganger clones (Anti-existence A, B , and C) of your current party. I basically panned out the weaker and less useful party members for this fight because the people you select stay behind to deal with the endless clone supply. I basically used the guns for the majority of the battle bridging over to the broadsword on the rengeki and then returning to the dual guns at the double trigger. It seemed to work well and the guns provided a lot more mobility than the other side arms. Plus I like how continuous fire can keep a target airborne and unable to mount a counter attack.
After three waves of clone battles you arrive at the core which has three targets to contend with. I began by removing some of these targets by getting rid of the right and left cores so I can focus on breaking the shield of the central core. Once this is done you have the final battle with the central core where you have to shave off roughly 6,000 HP.
After this battle you have the ending sequence along with some post game emails that I choose to read. For anyone interested my party was around level 132 when I started these final battles.