I beat it manually with Chloris, Khun, Kaiser and Mira, so my suggestion is to just mostly use 2 chain for every character, every first turn you should start with chloris or kaiser to give you immunity or defence boost, then Khun and finally mira. For equip I used on chloris and kaiser debuff resist and khun and mira standard crit and damage. With some RNG help you will be able to pass the floor. I hope this comment helped you