F!Corrin

Swift sparrow would probably pair better with the +spd, and once +10'd she will have a pretty solid speed on player phase and will be able to double most, with that, you may be able to give her a chill spd or threaten spd to insure you get those doubles

Here’s a build I run for upper tier AA. She’s +Atk -Res, because there’s fewer sources of magic damage at high scores. Makes DC useless except for scoring too, so don’t worry about it. Running Brazen in the A slot is a good idea.
Dark Breath + Windsweep + Phantom Speed (51 speed for calculating Windsweep) guarantees her debuffing the enemy team, while not receiving any counterattacks. Swift Sparrow conflicts with Windsweep, so don’t use both.