Clearly not the best run, but this is how you get my score of 870,520. I use Andras on the first team because she kills the first phase of Clara faster than the Oghma team, and speed is everything for points here, since you’re killing mobs for switch points, and you need the 2nd phase as soon as possible. The best I’ve gotten to kill the first phase was around 1:30, but that was like max dps from everyone , and I haven’t replicated it since lol. For my run with 870,520, I finished the first phase at 1:28.
When using Chrom, make sure you aim at least one of the first 2 weapon skills a little bit below her, so that you don’t chain her fully in 2 weapon skills, since you need the mobs to change to Garam. I’m not sure how to change Clara’s position when she teleports, but if she teleports to the left, you should reset the run. If she teleports up, attack the mobs near Nari and Eunha. If she teleports to the right, go after the mobs that Kanna will go after, so that you get her to apply her mark debuff as soon as possible, as you need as much damage for Garam’s team (Remember, Eunha’s atk debuff mark overrides Kanna’s def debuff mark).
Other than that good luck with the rng, because oof it’s rough getting the damage and speed.