Background: Throughout Ooku, we the player collect Hanafuda cards that lower the difficulty of the final boss of the event. However, if one decides to forego the Hanafuda cards, the final boss of Ooku being the Third Beast of Humanity: Beast III/Lapse is the single hardest boss alongside Beast III/Rapture in all of the game with few teams even having a shot at beating it. Along with having the best team compositions, the player engaging in this fight must know the game inside and out with knowledge of its mechanics thorogly drilled into them.
Only then, can they defeat possibly the single most difficult boss in Fate/Grand Order history.
Full Clear by another player on the JP Server using basically my same team composition: