This is just a demonstration of the highest possible battle score from a single battle. Battles with consecutive encounters (e.g., the very first battle in the game) seem to add battle scores together, giving the illusion of higher battle scores.
Basically, due to how the game rounds down every calculation, you need the points per second to be a divisor of 10000 for a particular battle to have the potential to have the highest possible battle score. This is easily done with a battle with two really weak enemies (compared to your party). You also don't want to waste time with characters running up to the enemies to perform physical attacks or for spells to travel across the stage, so you want enemies with an exclusive weakness to lightning and no resistance to magic. Hoplites are best served for this purpose. You also need your supporting party to wear Aurora Scarves so they will act immediately at battle start. Finally, getting a preemptive strike multiplies the final battle score by 1.2, so you need to achieve a preemptive strike; of course Deceptisols guarantee this.
Start the battle in Relentless Assault and..., well, watch the fireworks fly. Have you ever complained about how the game plays itself? You haven't seen a battle like this.
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