Alche, Serendia, and Arines are disposable, thus 2nd round should start with Angelica. My Angelica is +3, but that isn't quite enough to kill 8.  Instead of using Astrid+Angelica, Zenith+Ventana would also work.

1. ★6 Arines+9
2. ★6 Ebony+9
3. ★6 Veronia+9
4. ★6 Alche+9 (Kill 2, 4, 6, 7)
5. ★6 Serendia+9
6. ★5 Octavia+4 (Kill 3, 5, 9)
7. ★6 Angelica+5 (Kill 8, 10)
8. ★6 Astrid+6
9. ★6 Zakan+6

This 10-man party also achieved 17 turns.  If Esther can kill 8 instantly, it might be possible to get 16 turns.