-Pre-Chapter Shopping: Arcthunder x3, Beast Killer forging for +1 Mt and +10 Hit
-Tonics: Robin (HP, Mag, Def), Morgan (HP, Str, Def), Chrom (Str), Lucina (Str)
-Note that a great deal of stuff is going to be YOLO from here on out, depending on skillsets. When in doubt, kite, but the Rescue staves are there if Rescue bombing becomes a necessity.
-If Dance not needed for either above, Dance Robin and move into Sorc range (use the Levin Sword if no Hawkeye)
-Move Robin into Sorc range if not there already
-Next get the War Cleric
-Use Rally Speed to double and kill Swordmaster
-Morgan should be able to one-shot her with Yewfelle (one-round, if she has Aegis+).