Two ways to do this easy. First is to setup your group with Vlad, Ignis, Energi 1417 and Gil then burst a 4 enemy party with Lunar Stinger,Prominence Arrow, Catastrophe, and Tempest. This is a guarantee 55 hit combo. The second is to fight a boss with a ton of HP, like the Bulter Arena fight or Final boss, and just have a crazy high speed stat so as to get in several attacks before their turn. Either way works great! Hope the video helps!