Well yes, Sniper Shot an extra 10% Atk and 5% Def decrease (or 0% Def decrease if your Tyr isn't Awakened).

And jesus christ, your Thunder team is leagues above mine. Assuming you have like 60% Assault, I don't see you having any issues whatsoever. Just unload everything and full Burst on turn5/6 and dead. Well, that's how I'd assume it goes, without seeing how the event pans out.