Which Micaiah to build?

+Res/-Def. She becomes an extremely good mage tank, can ploy practically every unit in the game, and can deal a lot of damage with Iceberg.

There's also the Desperation + Brash Assault build to make her more offensive, so that's a thing.

I'm inclined to go with +Res / -Def because it allows her to activate her Ploys more easily and tank magic hits better. I'm not sure how much of her Physical match-ups will be affected, but her Def is already pretty low and her Spd isn't stellar either, so she is most likely going to die to anything Physical anyway, regardless if Def were neutral.

+Res -Def; Some Tanky Armor Mages can actually kill Micaiah with Armor buffs, like LA Lyn. She might also deal more Special damage.