-Atk Karla Special

I got a +Spd -Atk Karla from the legendary banner, she's my first and with a perfect boon so I'm happy with her. I plan on going the speed demon route with L&D and Desperation/Wrath and the Flashing Blade seal with a 2 turn special. I'm torn between keeping Draconic Aura, a steady +14 damage, or switching to Luna which will do more on any enemy with 28+ Def. Any thoughts on which is better?

Also, I'm not giving her Moonbow as my merged Soleil has the 1 turn Moonbow/Wrath combo.