I'm managing a delicate balance with a small barrier bc I especially don't want my barrier to be stolen. The sure way to sustain without visible buffs while still doing damage is with the Blaze Dingo I just got recently. My Fallen Cecilia is built more in the res department, and Shimadra Staff makes their jobs quite easier.

Meanwhile, Kawerick has Violin, and Tenebria has Etica Scepter. A combination of Sleep, Provoke, and Silence can prevent the mobs from buffing Mercedes, and in case they do, Kawerick being the fastest unit in my team can strip her and continue the assault.