Epic Seven Dagger Sicar Banshee 13 with all base 3* earth units Featuring Fluri & 3 ungearded units 

IMPORTANT NOTE: I used random ungearded 3* units. For the reputation make sure you use three 3* base EARTH units.
The trick here is 200% Effect Res and skills off.
200% Effect res is 100% immune to the banshee.
If you can't pull off 200% ER just get as close as you can
160%ER+ should work fine if flurry is relatively fast.
Justice For All is not required but sure helps. If you don't have JFA then I recommend Rise of the Monarch for constant shields or Proof of Valor to reduce incoming damage.
Enjoy what is probably the easiest Dagger Sicar mission in the game.
All it costs is 10-15 minutes of your life LOL.
Obviously you could use other 3* units to speed this up.
Jecht, SC Pearlhorizion, and SC Roozid with Fluri and this is over very fast. Pearl does surprising damage here even at Level 50.
Video is double speed so it doesn't take forever (and it makes Fluri sound hilarious)