https://www.youtube.com/watch?v=Z_rtH5pzovw
general endgame OTK kill guide if you're interested in something to build long term/for SPEED. General idea is
>build to OD1-OD2 on turn 1
>Single Use buffs (buffs that last X turns and just give you 2x right away, Seira has this atm) + Karen +
>kill

The DPS slot is a freebie so you can use someone like Sumomomomo or whoever is the weakness. Lot of LB3 required so thats its endgame but its pretty flexible depending on how much firepower you need. For example you can squeeze in the Yanagi + Yui combo which lets you pop off on turn 1 with OD. Mari SS5 + Yui + Karen is also pretty sick (LB4 Karen Unison required).