Have Genny heal whichever unit needs it the most, then let the enemy go. Then have Mae, Celica, Nomah (use Saggitae) and Catria continue to bombard the remaining Witches with magic. Your illusory soldiers will take their turn, either defeating or significantly damaging at least one witch when you regain control, have Est and Conrad kill the witches on the east side of the plains, then move Leon north into the trees so he can reach and defeat one of the witches immediately to the west.

During the enemy's turn, Witches will engage with Est, Mae, and your Illusory Soldiers, likely taking out a couple of your illusions but not doing sufficient damage to any of your living soldiers. Boey, Mae, Nomah, and Celica should move in to engage as well, while the rest of your units should fall back until you’ve cleared out the witches-try to keep them in a tight formation at the south end of the plain near the cliffs, or near the southest edge of the fortress. Move Genny north to the forest tile three spaces above her starting position, then cast invoke-as always, enemies in this game just love wasting their time on Illusory Soldiers, and you’ll want to keep them distracted so you can take all nine witches out without any casualties. Her resistance is sufficiently high to deal with multiple Witch attacks, and her speed will keep her attacking them twice (though she won't always land every hit.) Send Conrad in close so they’ll be attracted to him instead of your lower resistance units, then have Leon move just close enough to attack whichever of the witches on the northeast you'd like. We must be closing in on the end of Celica’s journey! Start by sending Est in to engage the Witches on the northeast. This is one of those battles where the game throws a whole lot of all the worst things at you, and then adds a Cantor on top of that to make things even more annoying.

Fire emblem echoes duma carving