Actually since the Virtue flies, she will cast her buffs, (say Mirror Image, Mistform, Air Shield, Resist Lighting) then set her to attack (1 Round) to get close to masses of the enemy, then cast with the Last order being casting spells. She'll do the smart thing and chaincast Shockwave as long as she has nearby units that the game finds feasible to cast on (I think as long as the squares are 50% full of units around her)